Signature of Proton–Hole Transfer in Hydrogen-Bonded Solids at 10 K
Kensei Kitajima, Yoichi Nakai, Masashi Tsuge, Naoki Watanabe
The Journal of Physical Chemistry Letters, 28 Nov. 2024
Scientific journal

Methane Formation Efficiency on Icy Grains: Role of Adsorption States
Masashi Tsuge, Germán Molpeceres, Yuri Aikawa, Naoki Watanabe
The Astrophysical Journal, 973, 2, 80, 80, American Astronomical Society, 20 Sep. 2024, [Peer-reviewed], [Lead author, Corresponding author], ［Internationally co-authored］, [International Magazine]
Scientific journal, Abstract

Methane (CH₄) is one of the major components of the icy mantle of cosmic dust prevalent in cold, dense regions of interstellar media, playing an important role in the synthesis of complex organic molecules and prebiotic molecules. Solid CH₄ is considered to be formed via the successive hydrogenation of C atoms accreting onto dust: C + 4H → CH₄. However, most astrochemical models assume this reaction on the ice mantles of dust to be barrierless and efficient, without considering the states of adsorption. Recently, we found that C atoms exist in either the physisorbed or chemisorbed state on compact amorphous solid water, which is analogous to an interstellar ice mantle. These distinct adsorption states considerably affect the hydrogenation reactivity of the C atom. Herein, we elucidate the reactivities of physisorbed and chemisorbed C atoms with H atoms via sequential deposition and codeposition processes. The results indicate that only physisorbed C atoms can produce CH₄ on ice. Combining this finding with a previous estimate for the fraction of physisorbed C atoms on ice, we determined the upper limit for the conversion of C atoms into CH₄ to be 30%., 46157276

Photodesorption efficiency of OH radical on the ice surface in the wavelength range from ultraviolet to visible
Ni-En Sie, Masashi Tsuge, Yoichi Nakai, Naoki Watanabe
Chemical Physics Letters, 848, 141384, 141384, Elsevier BV, Aug. 2024, [Peer-reviewed]
Scientific journal, 42098847

Carbon Atom Condensation on NH₃–H₂O Ices. An Alternative Pathway to Interstellar Methanimine and Methylamine
Germán Molpeceres, Masashi Tsuge, Kenji Furuya, Naoki Watanabe, David San Andrés, Víctor M. Rivilla, Laura Colzi, Yuri Aikawa
The Journal of Physical Chemistry A, 128, 3874, 3889, American Chemical Society (ACS), 06 May 2024, [Peer-reviewed]
Scientific journal, 42098847

Coverage dependent H2 desorption energy: a quantitative explanation based on encounter desorption mechanism
Qingkuan Meng, Qiang Chang, Gang Zhao, Donghui Quan, Masashi Tsuge, Xia Zhang, Yong Zhang, Xiao-Hu Li
Monthly Notices of the Royal Astronomical Society, 526, 2, 2394, 2399, Oxford University Press (OUP), 26 Sep. 2023, [Peer-reviewed]
Scientific journal, ABSTRACT

Recent experiments show that the desorption energy of H2 on a diamond-like carbon surface depends on the H2 coverage of the surface. We aim to quantitatively explain the coverage dependent H2 desorption energy measured by the experiments. We derive a math formula to calculate an effective H2 desorption energy based on the encounter desorption mechanism. The effective H2 desorption energy depends on two key parameters, the desorption energy of H2 on H2 substrate and the ratio of H2 diffusion barrier to its desorption energy. The calculated effective H2 desorption energy qualitatively agrees with the coverage dependent H2 desorption energy measured by the experiments if the values of these two parameters in literature are used in the calculations. We argue that the difference between the effective H2 desorption energy and the experimental results is due to the lack of knowledge about these two parameters. So, we recalculate these two parameters based on experimental data. Good agreement between theoretical and experimental results can be achieved if these two updated parameters are used in the calculations.

Surface diffusion of carbon atoms as a driver of interstellar organic chemistry
Masashi Tsuge, Germán Molpeceres, Yuri Aikawa, Naoki Watanabe
Nature Astronomy, 7, 1351, 1358, SPRINGER NATURE, 14 Sep. 2023, [Peer-reviewed], [Lead author, Corresponding author], [International Magazine]
Scientific journal, Many interstellar complex organic molecules (COMs) are believed to be produced on the surfaces of icy grains at low temperatures. Atomic carbon is considered responsible for the skeletal evolution processes, such as C–C bond formation, via insertion or addition reactions. Before reactions, C atoms must diffuse on the surface to encounter reaction partners; therefore, information on their diffusion process is critically important for evaluating the role of C atoms in the formation of COMs. In situ detection of C atoms on ice was achieved by a combination of photostimulated desorption and resonance-enhanced multiphoton ionization methods. We found that C atoms weakly bound to the ice surface diffused above approximately 30 K and produced C2 molecules. The activation energy for C-atom surface diffusion was experimentally determined to be 88 meV (1,020 K), indicating that the diffusive reaction of C atoms is activated at approximately 22 K on interstellar ice. The facile diffusion of C atoms at temperatures above 22 K on interstellar ice opens a previously overlooked chemical regime where the increase in complexity of COMs is driven by C atoms. Carbon addition chemistry can be an alternative source of chemical complexity in translucent clouds and protoplanetary disks with crucial implications in our current understanding on the origin and evolution of organic chemistry in our Universe., 42098848

Radical reactions on interstellar icy dust grains: Experimental investigations of elementary processes
Masashi TSUGE, Naoki WATANABE
Proceedings of the Japan Academy, Series B, 99, 4, 103, 130, Japan Academy, 28 Apr. 2023, [Peer-reviewed], [Invited], [Lead author]
Scientific journal, 32183705

Infrared spectra of isoquinolinium (iso-C₉H₇NH⁺) and isoquinolinyl radicals (iso-C₉H₇NH and 1-, 3-, 4-, 5-, 6-, 7-, and 8-iso-HC₉H₇N) isolated in solid para-hydrogen
Prasad Ramesh Joshi, Masashi Tsuge, Chih-Yu Tseng, Yuan-Pern Lee
Physical Chemistry Chemical Physics, 25, 11934, 11950, Royal Society of Chemistry (RSC), 20 Feb. 2023, [Peer-reviewed], [Corresponding author]
Scientific journal, Protonated polycyclic aromatic nitrogen heterocycles (H⁺PANH) are prospective candidates that might contribute to the interstellar unidentified infrared (UIR) emission bands because protonation enhances the relative intensities of bands near 6.2,..., 32183705

Direct Determination of the Activation Energy for Diffusion of OH Radicals on Water Ice
A. Miyazaki, M. Tsuge, H. Hidaka, Y. Nakai, N. Watanabe
The Astrophysical Journal Letters, 940, 1, L2, L2, American Astronomical Society, 01 Nov. 2022, [Peer-reviewed]
Scientific journal, Abstract

Using a combination of photostimulated desorption and resonance-enhanced multiphoton ionization methods, the behaviors of OH radicals on the surface of an interstellar ice analog were monitored at temperatures between 54 and 80 K. The OH number density on the surface of ultraviolet-irradiated compact amorphous solid water gradually decreased at temperatures above 60 K. Analyzing the temperature dependence of OH intensities with the Arrhenius equation, the decrease can be explained by the recombination of two OH radicals, which is rate-limited by thermal diffusion of OH. The activation energy for surface diffusion was experimentally determined for the first time to be 0.14 ± 0.01 eV, which is larger than or equivalent to those assumed in theoretical models. This value implies that the diffusive reaction of OH radicals starts to be activated at approximately 36 K on interstellar ice.

Chiral Ice Crystals in Space
Akira Kouchi, Takashi Shimonishi, Tomoya Yamazaki, Masashi Tsuge, Naoki Nakatani, Kenji Furuya, Hiromasa Niinomi, Yasuhiro Oba, Tetsuya Hama, Hiroyasu Katsuno, Naoki Watanabe, Yuki Kimura
Chirality - New Insights [Working Title], IntechOpen, 22 Aug. 2022, [Peer-reviewed], [Invited]
In book, We observed the formation of CO, CH3OH, and H2O ices using a cryogenic transmission electron microscope, to determine if chiral ice crystals could form under the conditions of interstellar molecular clouds and young stellar objects (protoplanetary disks) and to clarify the crystalline structure of these ices. Our results suggest that the following ice crystals are chiral: crystalline CO (α-CO) formed on amorphous H2O (a-H2O) grains in a 10-K molecular cloud, crystalline CH3OH formed by the heating of amorphous CH3OH on a-H2O grains at 40–60 K in young stellar objects, and several polymorphs of hydrogen-ordered cubic ice crystals formed by the heating of a-H2O at 80–100 K and direct condensation at 120–140 K in protoplanetary disks. We also investigated candidates for other chiral ices using published data. We found that NH3 I and NH3·H2O I are chiral at low temperature and pressure conditions. If one-handed circularly polarized light is irradiated during the nucleation of these chiral ice crystals, homochiral crystals can be formed. These results have important implications for the origin of interstellar organic molecule homochirality.

Infrared and Laser-Induced Fluorescence Spectra of Sumanene Isolated in Solid para-Hydrogen
Isabelle Weber, Masashi Tsuge, Pavithraa Sundararajan, Masaaki Baba, Hidehiro Sakurai, Yuan-Pern Lee
The Journal of Physical Chemistry A, 126, 32, 5283, 5293, American Chemical Society (ACS), 18 Aug. 2022, [Peer-reviewed]
Scientific journal

Penetration of Nonenergetic Hydrogen Atoms into Amorphous Solid Water and their Reaction with Embedded Benzene and Naphthalene
Masashi Tsuge, Akira Kouchi, Naoki Watanabe
The Astrophysical Journal, 933, 2, 138, 138, American Astronomical Society, 01 Jul. 2022, [Peer-reviewed], [Lead author, Corresponding author]
Scientific journal, Abstract

Chemical processes on the surface of icy grains play an important role in the chemical evolution in molecular clouds. In particular, reactions involving nonenergetic hydrogen atoms accreted from the gaseous phase have been extensively studied. These reactions are believed to effectively proceed only on the surface of the icy grains; thus, molecules embedded in the ice mantle are not considered to react with hydrogen atoms. Recently, Tsuge et al. suggested that nonenergetic hydrogen atoms can react with CO molecules even in ice mantles via diffusive hydrogenation. This investigation was extended to benzene and naphthalene molecules embedded in amorphous solid water (ASW) in the present study, which revealed that a portion of these molecules could be fully hydrogenated in astrophysical environments. The penetration depths of nonenergetic hydrogen atoms into porous and nonporous ASW were determined using benzene molecules to be >50 and ∼10 monolayers, respectively (1 monolayer ≈ 0.3 nm)., 32183705

Modelling the Radical Chemistry on Ice Surfaces: An Integrated Quantum Chemical and Experimental Approach
W. M. C. Sameera, Bethmini Senevirathne, Thanh Nguyen, Yasuhiro Oba, Atsuki Ishibashi, Masashi Tsuge, Hiroshi Hidaka, Naoki Watanabe
Frontiers in Astronomy and Space Sciences, 9, 890161, Frontiers Media SA, 30 May 2022, [Peer-reviewed], [Invited]
English, Scientific journal, Heterogeneous radical processes on ice surfaces play a vital role in the formation of building blocks of the biologically relevant molecules in space. Therefore, quantitative mechanistic details of the radical binding and radical reactions on ices are crucial in rationalizing the chemical evolution in the Universe. The radical chemistry on ice surfaces was explored at low temperatures by combining quantum chemical calculations and laboratory experiments. A range of binding energies was observed for OH, HCO, CH₃, and CH₃O radicals binding on ices. Computed reaction paths of the radical reactions on ices, OCS + H and PH₃ + D, explained the experimentally observed products. In both radical reactions, quantum tunnelling plays a key role in achieving the reactions at low temperatures. Our findings give quantitative insights into radical chemistry on ice surfaces in interstellar space and the planetary atmospheres.

UV-Induced Formation of Ice XI Observed Using an Ultra-High Vacuum Cryogenic Transmission Electron Microscope and its Implications for Planetary Science
Akira Kouchi, Yuki Kimura, Kensei Kitajima, Hiroyasu Katsuno, Hiroshi Hidaka, Yasuhiro Oba, Masashi Tsuge, Tomoya Yamazaki, Kazuyuki Fujita, Tetsuya Hama, Yukihiro Takahashi, Shunichi Nakatsubo, Naoki Watanabe
Frontiers in Chemistry, 9, 799851, 799851, Frontiers Media SA, 08 Dec. 2021, [Peer-reviewed]
Scientific journal, The occurrence of hydrogen atom-ordered form of ice Ih, ice XI, in the outer Solar System has been discussed based on laboratory experiments because its ferroelectricity influences the physical processes in the outer Solar System. However, the formation of ice XI in that region is still unknown due to a lack of formation conditions at temperatures higher than 72 K and the effect of UV-rays on the phase transition from ice I to ice XI. As a result, we observed the UV-irradiation process on ice Ih and ice Ic using a newly developed ultra-high vacuum cryogenic transmission electron microscope. We found that ice Ih transformed to ice XI at temperatures between 75 and 140 K with a relatively small UV dose. Although ice Ic partially transformed to ice XI at 83 K, the rate of transformation was slower than for ice Ih. These findings point to the formation of ice XI at temperatures greater than 72 K via UV irradiation of ice I crystals in the Solar System; icy grains and the surfaces of icy satellites in the Jovian and Saturnian regions.

Measurements of Ortho-to-para Nuclear Spin Conversion of H2 on Low-temperature Carbonaceous Grain Analogs: Diamond-like Carbon and Graphite
Masashi Tsuge, Akira Kouchi, Naoki Watanabe
The Astrophysical Journal, 923, 1, 71, American Astronomical Society, 01 Dec. 2021, [Peer-reviewed], [Lead author, Corresponding author]
English, Scientific journal,
Hydrogen molecules have two nuclear spin isomers: ortho-H₂ and para-H₂. The ortho-to-para ratio (OPR) is known to affect chemical evolution as well as gas dynamics in space. Therefore, understanding the mechanism of OPR variation in astrophysical environments is important. In this work, the nuclear spin conversion (NSC) processes of H₂ molecules on diamond-like carbon and graphite surfaces are investigated experimentally by employing temperature-programmed desorption and resonance-enhanced multiphoton ionization methods. For the diamond-like carbon surface, the NSC time constants were determined at temperatures of 10–18 K and from 3900 ± 800 s at 10 K to 750 ± 40 s at 18 K. Similar NSC time constants and temperature dependence were observed for a graphite surface, indicating that bonding motifs (sp³ or sp² hybridization) have little effect on the NSC rates., 32183705

Two-Body Metastable Dissociation of n-Pentane and n-Hexane Triplet Dications in Intense Femtosecond-Laser Fields
Kennosuke Hoshina, Tatsuro Shirota, Masashi Tsuge
The Journal of Physical Chemistry A, 125, 43, 9508, 9517, American Chemical Society ({ACS}), 04 Nov. 2021, [Peer-reviewed]
Scientific journal, 12213477

Transmission Electron Microscopy Study of the Morphology of Ices Composed of H2O, CO2, and CO on Refractory Grains
Akira Kouchi, Masashi Tsuge, Tetsuya Hama, Yasuhiro Oba, Satoshi Okuzumi, Sin-iti Sirono, Munetake Momose, Naoki Nakatani, Kenji Furuya, Takashi Shimonishi, Tomoya Yamazaki, Hiroshi Hidaka, Yuki Kimura, Ken-ichiro Murata, Kazuyuki Fujita, Shunichi Nakatsubo, Shogo Tachibana, Naoki Watanabe
The Astrophysical Journal, 918, 2, 45, 45, American Astronomical Society, 06 Sep. 2021, [Peer-reviewed], [Corresponding author]
English, Scientific journal

Formation of chiral CO polyhedral crystals on icy interstellar grains
Akira Kouchi, Masashi Tsuge, Tetsuya Hama, Hiromasa Niinomi, Naoki Nakatani, Takashi Shimonishi, Yasuhiro Oba, Yuki Kimura, Sin-iti Sirono, Satoshi Okuzumi, Munetake Momose, Kenji Furuya, Naoki Watanabe
Monthly Notices of the Royal Astronomical Society, 505, 1, 1530, 1542, Oxford University Press (OUP), 27 Apr. 2021, [Peer-reviewed]
Scientific journal,
The crystallinity and morphology of solid CO on icy interstellar grains were examined by observing the deposition, crystallisation, and UV and electrons irradiation of solid CO using transmission electron microscopy. Herein, we found that solid CO deposited in molecular clouds was crystalline, and that even if amorphous CO was deposited amorphous CO crystallised within 103 years at 10 K. Conversely, crystalline CO was not amorphised by UV rays or electron beam at 10 K. These results indicated the occurrence of chiral crystalline CO instead of amorphous CO in space. Furthermore, the large surface diffusion coefficients of CO on amorphous H2O and crystalline CO at 10 K facilitated the morphological equilibration of crystalline CO. Bad wetting of crystalline CO with amorphous H2O proved that the morphology of the ice grains was not spherical with an onion-like structure, as hitherto assumed, but rather it was a polyhedral crystalline CO attached to amorphous H2O. This has important implications for phenomena associated with the collision and subsequent sticking between ice grains, surface chemical reactions, non-thermal desorption of molecules and the origin of homochirality in interstellar biomolecules.

Rapid Ortho-to-para Nuclear Spin Conversion of H2 on a Silicate Dust Surface
M. Tsuge, T. Namiyoshi, K. Furuya, T. Yamazaki, A. Kouchi, N. Watanabe
The Astrophysical Journal, 908, 2, 234, 234, American Astronomical Society, 26 Feb. 2021, [Peer-reviewed], [Lead author]
Scientific journal

Behavior of Hydroxyl Radicals on Water Ice at Low Temperatures
Masashi Tsuge, Naoki Watanabe
Accounts of Chemical Research, 54, 3, 471, 480, American Chemical Society ({ACS}), 02 Feb. 2021, [Peer-reviewed], [Invited], [Lead author]
English, Scientific journal

Delivery of Electrons by Proton-Hole Transfer in Ice at 10 K: Role of Surface OH Radicals
Kensei Kitajima, Yoichi Nakai, W. M. C. Sameera, Masashi Tsuge, Ayane Miyazaki, Hiroshi Hidaka, Akira Kouchi, Naoki Watanabe
The Journal of Physical Chemistry Letters, 12, 1, 704, 710, American Chemical Society ({ACS}), 14 Jan. 2021, [Peer-reviewed]
English, Scientific journal

Photostimulated desorption of OH radicals from amorphous solid water: Evidence for the interaction of visible light with an OH-ice complex
A. Miyazaki, N. Watanabe, W. M. C. Sameera, Y. Nakai, M. Tsuge, T. Hama, H. Hidaka, A. Kouchi
Physical Review A, 102, 5, 52822, American Physical Society (APS), 20 Nov. 2020, [Peer-reviewed]
English, Scientific journal

Infrared Spectra of Monohydrogenated Aniline, ortho- and para-HC6H5NH2, Generated in Solid para-Hydrogen
Masashi Tsuge, Yu-Hsuan Chen, Yuan-Pern Lee
The Journal of Physical Chemistry A, 124, 37, 7500, 7510, American Chemical Society ({ACS}), 17 Sep. 2020, [Peer-reviewed], [Lead author, Corresponding author]
Scientific journal

UV-ray irradiation never causes amorphization of crystalline CO2: A transmission electron microscopy study
Masashi Tsuge, Thanh Nguyen, Yasuhiro Oba, Tetsuya Hama, Akira Kouchi, Naoki Watanabe
Chemical Physics Letters, 760, 137999, 137999, Elsevier BV, 14 Sep. 2020, [Peer-reviewed], [Lead author, Corresponding author]
Scientific journal

Diffusive Hydrogenation Reactions of CO Embedded in Amorphous Solid Water at Elevated Temperatures ∼70 K
Masashi Tsuge, Hiroshi Hidaka, Akira Kouchi, Naoki Watanabe
The Astrophysical Journal, 900, 187, 01 Sep. 2020, [Peer-reviewed], [Lead author, Corresponding author]
Scientific journal

Infrared spectroscopy of H+(CO)2 in the gas phase and in para-hydrogen matrices
Daniel Leicht, Brandon M. Rittgers, Gary E. Douberly, J. Philipp Wagner, David C. McDonald, II, Daniel T. Mauney, Masashi Tsuge, Yuan-Pern Lee, Michael A. Duncan
The Journal of Chemical Physics, 153, 8, 84305, 84305, AIP Publishing, 28 Aug. 2020, [Peer-reviewed], [Corresponding author]
Scientific journal

Experimental Approach to Physicochemical Hydrogen Processes on Cosmic Ice Dust
Naoki Watanabe, Masashi Tsuge
Journal of the Physical Society of Japan, 89, 51015, 15 May 2020, [Peer-reviewed], [Invited]
English, Scientific journal

Infrared Spectra of Isomers of Protonated Aniline in Solid para-Hydrogen
Masashi Tsuge, Yu-Hsuan Chen, Yuan-Pern Lee
The Journal of Physical Chemistry A, 124, 11, 2253, 2263, American Chemical Society ({ACS}), 19 Mar. 2020, [Peer-reviewed], [Lead author, Corresponding author]
English, Scientific journal

Thermal decomposition of the HXeCl···H2O complex in solid xenon: Experimental characterization of the two-body decomposition channel
Masashi Tsuge, Markku Räsänen, Leonid Khriachtchev
Chemical Physics Letters, 739, 136987, 136987, Elsevier {BV}, Jan. 2020, [Peer-reviewed], [Lead author, Corresponding author]
English, Scientific journal, The thermal decomposition process of HXeCl···H2O in solid Xe is studied, and HCl···H2O is identified as a decomposition product. The production is due to the two-body (2B) decomposition of HXeCl moiety, in agreement with theoretical predictions. Two types of 2B decomposition paths are predicted: catalytic and unimolecular 2B decompositions, where water molecule plays different roles. In an experiment to selectively produce HXeCl···D2O, only HCl···D2O is observed as a thermal decomposition product, indicating the occurrence of unimolecular 2B decomposition, where water molecule serves as a spectator. The activation energy for this decomposition process is experimentally determined to be 15 kJ mol−1.

Electronic and vibrational structure in the S and S1 states of corannulene
Ayumi Kanaoka, Hiromi Tohyama, Sachi Kunishige, Toshiharu Katori, Akiko Nishiyama, Masatoshi Misono, Naofumi Nakayama, Hidehiro Sakurai, Masashi Tsuge, Masaaki Baba
The Journal of Chemical Physics, 151, 23, 234305, 21 Dec. 2019, [Peer-reviewed]
English, Scientific journal, © 2019 Author(s). Corannulene is a nonplanar aromatic hydrocarbon also known as a buckybowl. Its electronic and vibrational structure has been investigated by analyzing its fluorescence excitation spectrum and dispersed fluorescence spectrum in a supersonic jet. Its spectral features are in keeping with the expectation, confirmed by some previous results, that it has fivefold or C5v symmetry. The observed prominent vibronic bands in the S1 ← S0 transition have been assigned to e1 and e2 bands on the basis of theoretical calculations so that the S1 state was assigned to 1E2. The symmetry adapted cluster configuration interaction calculation supports this assignment of the S1 electronic state, although the time-dependent density functional theory calculation suggests that the S1 state is 1A2. It has also been shown that the normal coordinates for strong vibronic bands mainly include out-of-plane vibrational motion. The rotational envelopes are well explained by taking account of the Coriolis interaction between the degenerate vibrational and rotational levels. The mechanism of bowl-to-bowl inversion is also discussed with the results of theoretical calculations regarding the barrier to inversion and metastable conformation.

Infrared spectrum of hydrogenated corannulene rim-HC20H10 isolated in solid para-hydrogen
Pavithraa Sundararajan, Masashi Tsuge, Masaaki Baba, Hidehiro Sakurai, Yuan-Pern Lee
The Journal of Chemical Physics, 151, 4, 44304, 28 Jul. 2019, [Peer-reviewed]
English, Scientific journal, © 2019 Author(s). Hydrogenated polycyclic aromatic hydrocarbons have been proposed to be carriers of the interstellar unidentified infrared (UIR) emission bands and the catalysts for formation of H2; spectral characterizations of these species are hence important. We report the infrared (IR) spectrum of mono-hydrogenated corannulene (HC20H10) in solid para-hydrogen (p-H2). In experiments of electron bombardment of a mixture of corannulene and p-H2 during deposition of a matrix at 3.2 K, two groups of spectral lines increased with time during maintenance of the matrix in darkness after deposition. Lines in one group were assigned to the most stable isomer of hydrogenated corannulene, rim-HC20H10, according to the expected chemistry and a comparison with scaled harmonic vibrational wavenumbers and IR intensities predicted with the B3PW91/6-311++G(2d,2p) method. The lines in the other group do not agree with predicted spectra of other HC20H10 isomers and remain unassigned. Alternative hydrogenation was achieved with H atoms produced photochemically in the infrared-induced reaction Cl + H2 (v = 1) → H + HCl in a Cl2/C20H10/p-H2 matrix. With this method, only lines attributable to rim-HC20H10 were observed, indicating that hydrogenation via a quantum-mechanical tunneling mechanism produces preferably the least-energy rim-HC20H10 regardless of similar barrier heights and widths for the formation of rim-HC20H10 and hub-HC20H10. The mechanisms of formation in both experiments are discussed. The bands near 3.3 and 3.4 μm of rim-HC20H10 agree with the UIR emission bands in position and relative intensity, but other bands do not match satisfactorily with the UIR bands.

Interactions of Atomic and Molecular Hydrogen with a Diamond-like Carbon Surface: H2 Formation and Desorption
Masashi Tsuge, Tetsuya Hama, Yuki Kimura, Akira Kouchi, Naoki Watanabe
The Astrophysical Journal, 878, 1, 23, IOP PUBLISHING LTD, 10 Jun. 2019, [Peer-reviewed], [Lead author, Corresponding author]
English, Scientific journal, The interactions of atomic and molecular hydrogen with bare interstellar dust grain surfaces are important for understanding H-2 formation at relatively high temperatures (>20 K). We investigate the diffusion of physisorbed H atoms and the desorption energetics of H-2 molecules on an amorphous diamond-like carbon (DLC) surface. From temperature-programmed desorption experiments with a resonance-enhanced multiphoton ionization (REMPI) method for H-2 detection, the H-2 coverage-dependent activation energies for H-2 desorption are determined. The activation energies decrease with increasing H-2 coverage and are centered at 30 meV with a narrow distribution. Using a combination of photostimulated desorption and REMPI methods, the time variations of the surface number density of H-2 following atomic and molecular hydrogen depositions are studied. From these measurements, we show that H-2 formation on a DLC surface is quite efficient, even at 20 K. A significant kinetic isotope effect for H-2 and D-2 recombination reactions suggests that H-atom diffusion on a DLC surface is mediated by quantum mechanical tunneling. In astrophysically relevant conditions, H-2 recombination due to physisorbed H-atoms is unlikely to occur at 20 K, suggesting that chemisorbed H atoms might play a role in H-2 formation at relatively high temperatures.

Infrared Spectrum of Protonated Corannulene H+C20H10 in Solid para-Hydrogen and its Potential Contribution to Interstellar Unidentified Infrared Bands
Pavithraa Sundararajan, Masashi Tsuge, Masaaki Baba, Yuan-Pern Lee
ACS Earth and Space Chemistry, 2, 10, 1001, 1010, American Chemical Society ({ACS}), 18 Oct. 2018, [Peer-reviewed]
English, Scientific journal

Activation of Molecular Hydrogen by Arylcarbenes
Enrique Mendez‐Vega, Mika Maehara, Akshay Hemant Raut, Joel Mieres‐Perez, Masashi Tsuge, Yuan‐Pern Lee, Wolfram Sander
Chemistry–A European Journal, 24, 70, 18801, 18808, 12 Oct. 2018, [Peer-reviewed]
English, Scientific journal

Infrared spectra of 3-hydroxy-(1H)-pyridinium cation and 3-hydroxy-(1H)-pyridinyl radical isolated in solid para-hydrogen
Masashi Tsuge, Chia-Peng Lai, Yuan-Pern Lee
The Journal of Chemical Physics, 149, 14306, 07 Jul. 2018, [Peer-reviewed], [Lead author, Corresponding author]
Scientific journal

Measurements of the Activation Energies for Atomic Hydrogen Diffusion on Pure Solid CO
Y. Kimura, M. Tsuge, V. Pirronello, A. Kouchi, N. Watanabe
The Astrophysical Journal Letters, 858, 2, American Astronomical Society, 10 May 2018, [Peer-reviewed]
English, Scientific journal, The diffusion of hydrogen atoms on dust grains is a key process in the formation of interstellar H2 and some hydrogenated molecules such as formaldehyde and methanol. We investigate the adsorption and diffusion of H atoms on pure solid CO as an analog of dust surfaces observed toward some cold interstellar regions. Using a combination of photostimulated desorption and resonance-enhanced multiphoton ionization methods to detect H atoms directly, the relative adsorption probabilities and diffusion coefficients of the H atoms are measured on pure solid CO at 8, 12, and 15 K. There is little difference between the diffusion coefficients of the hydrogen and deuterium atoms, indicating that the diffusion is limited by thermal hopping. The activation energies controlling the H-atom diffusion depend on the surface temperature, and values of 22, 30, and ∼37 meV were obtained for 8, 12, and 15 K, respectively.

Spectroscopy of prospective interstellar ions and radicals isolated in para-hydrogen matrices
Masashi Tsuge, Chih-Yu Tseng, Yuan-Pern Lee
Physical Chemistry Chemical Physics, 20, 8, 5344, 5358, Royal Society of Chemistry ({RSC}), 2018, [Peer-reviewed], [Lead author]
English, Scientific journal, para-Hydrogen (p-H2) serves as a new host in matrix-isolation experiments for an investigation of species of astrochemical interest. Protonated and mono-hydrogenated species are produced upon electron bombardment during deposition of p-H2 containing a precursor in a small proportion. The applications of this novel technique to generate protonated polycyclic aromatic hydrocarbons (H+PAH), protonated polycyclic nitrogen heterocycles (H+PANH), and their neutral counterparts, which are important in the identification of interstellar unidentified infrared emission bands, demonstrate its superiority over other methods. The clean production with little fragmentation, ease of distinction between protonated and neutral species, narrow lines and reliable relative infrared intensities of the lines, and broad coverage of the spectral range associated with this method enable us to assign the isomers unambiguously. The application of this method to the protonation of small molecules is more complicated partly because of the feasible fragmentation and reactions, and partly because of the possible proton sharing between the species of interest and H2, but, with isotopic experiments and secondary photolysis, definitive assignments are practicable. Furthermore, the true relative infrared intensities are critical to a comparison of experimental results with data from theoretical calculations. The spectra of a proton-shared species in solid p-H2 might provide insight into a search for spectra of proton-bound species in interstellar media. Investigations of hydrogenated species involving the photolysis of Cl2 or precursors of OH complement those using electron bombardment and provide an improved ratio of signal to noise. With careful grouping of observed lines after secondary photolysis and a comparison with theoretical predictions, various isomers of these species have been determined. This photolytic technique has been applied in an investigation of hydrogenated PAH and PANH, and the hydrogenation reactions of small molecules, which are important in interstellar ice and the evolution of life. The electronic transitions of molecules in solid p-H2 have been little investigated. The matrix shift of the origins of transitions and the spectral width seem to be much smaller than those of noble-gas matrices
these features might facilitate a direct comparison of matrix spectra with diffuse interstellar bands, but further data are required to assess this possibility. The advantages and disadvantages of applying these techniques of p-H2 matrix isolation to astrochemical research and their future perspectives are discussed.

Infrared spectra and anharmonic coupling of proton-bound nitrogen dimers N2–H+–N2, N2–D+–N2, and 15N2–H+–15N2 in solid para-hydrogen
Hsin-Yi Liao, Masashi Tsuge, Jake A. Tan, Jer-Lai Kuo, Yuan-Pern Lee
Physical Chemistry Chemical Physics, 19, 31, 20484, 20492, Royal Society of Chemistry ({RSC}), 13 Jul. 2017, [Peer-reviewed], [Corresponding author]
English, Scientific journal, The proton-bound nitrogen dimer, N-2-H+-N-2, and its isotopologues were investigated by means of vibrational spectroscopy. These species were produced upon electron bombardment of mixtures of N-2 (or N-15(2)) and para-hydrogen (p-H-2) or normal-D-2 (n-D-2) during deposition at 3.2 K. Reduced-dimension anharmonic vibrational Schrodinger equations were constructed to account for the strong anharmonic effects in these protonated species. The fundamental lines of proton motions in N-2-H+-N-2 were observed at 715.0 (NH+N antisymmetric stretch, nu(4)), 1129.6 (NH+N bend, nu(6)), and 2352.7 (antisymmetric NN/NN stretch, nu(3)) cm(-1), in agreement with values of 763, 1144, and 2423 cm(-1) predicted with anharmonic calculations using the discrete-variable representation (DVR) method at the CCSD/aug-cc-pVDZ level. The lines at 1030.2 and 1395.5 cm(-1) were assigned to combination bands involving n nu(2) + n4 (n = 1 and 2) according to theoretical calculations; nu(2) is the N-2 ... N-2 stretching mode. For N-15(2)-H+-N-15(2) in solid p-H-2, the corresponding major lines were observed at 710.0 (nu(4)), 1016.7 (nu(2) + nu(4)), 1124.3 (nu(6)), 1384.8 (2 nu(2) + nu(4)), and 2274.9 (nu(3)) cm(-1). For N-2-D+-N-2 in solid n-D-2, the corresponding major lines were observed at 494.0 (nu(4)), 840.7 (nu(2) + nu(4)), 825.5 (nu(6)), and 2356.2 (nu(3)) cm(-1). In addition, two lines at 762.0 (weak) and 808.3 cm(-1) were tentatively assigned to be some modes of N-2-H+-N-2 perturbed or activated by a third N-2 near the proton.

Infrared spectra of HSCS+, c-HSCS, and HCS2− produced on electron bombardment of CS2 in solid para-hydrogen
Masashi Tsuge, Yuan-Pern Lee
Physical Chemistry Chemical Physics, 19, 14, 9641, 9653, Royal Society of Chemistry ({RSC}), 13 May 2017, [Peer-reviewed], [Lead author, Corresponding author]
English, Scientific journal, We report infrared (IR) spectra of HSCS+, c-HSCS, HCS2-, and other species produced on electron bombardment of a mixture of CS2 and para-hydrogen (p-H-2) during deposition at 3.2 K. After maintenance of the deposited matrix in darkness for 12 h, the intensities of the absorption lines of HSCS+ at 2477.2 (v(1)), 1525.6 (v(2)), and 919.6 cm(-1) (v(3)) decreased through neutralization of HSCS+ with trapped electrons. During this period, the intensities of the lines of HCS2- at 2875.7 (v(1)), 1249.9 (v(5)), 1003.2 (v(6)), and 814.3 cm (1) (v(4)) increased due to reaction between H and CS2 . The intensities of the lines observed at 2312.7 and 889.0 cm(-1), which are assigned to the c-HSCS radical, increased after maintenance in darkness and greatly diminished after irradiation at 373 nm. The IR spectra of HSCS+, HCS2-, and c-HSCS are reported for the first time. The IR absorption lines of the t-HSCS radical, t-HC(S) SH, and c-HC(S) SH were also identified; their wavenumbers are similar to those reported for these species in an Ar matrix. The corresponding spectra of the C-13, S-34, and D isotopic variants of these species were observed. The assignments were made according to the expected chemical behavior, predicted potential energies of associated reactions, and a comparison of observed and predicted wavenumbers and their C-13, S-34, and D isotopic ratios. In contrast to the observed significant red shifts of the OH-stretching wavenumbers of HOCO+ and HOCS+ in solid p-H-2 compared to those in the gaseous phase due to proton sharing with H-2, the wavenumber of the HS-stretching mode of HSCS+ in solid p-H-2 (2477.2 cm(-1)) is similar to the anharmonic wavenumber of HSCS+ (2424 cm(-1)) predicted with the B3LYP/aug-cc-pVTZ method, indicating that the sharing of a proton between HSCS+ and neighboring H-2 molecules is insignificant.

Detection of Neutral Species in the MALDI Plume Using Femtosecond Laser Ionization: Quantitative Analysis of MALDI-MS Signals Based on a Semiequilibrium Proton Transfer Model
Tatsuro Shirota, Masashi Tsuge, Yasumasa Hikosaka, Koichi Soejima, Kennosuke Hoshina
JOURNAL OF PHYSICAL CHEMISTRY A, 121, 1, 31, 39, AMER CHEMICAL SOC, 09 Dec. 2016, [Peer-reviewed]
English, Scientific journal, We investigated neutral species in the matrix-assisted laser desorption and ionization (MALDI) plume using femtosecond laser ionization spectrometry with simultaneous measurement of the standard MALDI spectrum of the identical MALDI event induced by pulsed UV laser irradiation. The ratio of neutral species in the plume [A](p)/[M](p) (A = phenylalanine (Phe) or alanine (Ala), M = 2,5-dihydroxybenzoic acid (DHB)) was confirmed to be the same as that of the sample mixture in the range of [A](0)/[M](0) = 4 x 10(-4)-1, indicating the validity of the widely adopted approximation [A](p)/[M](p) = [A](0)/[M](0) in the reaction quotient of the proton transfer reaction MH+ + A reversible arrow M + AH(+). An effective parameter representing the extent of thermal equilibrium in the thermal proton transfer model is introduced for the first time. Numerical simulation based on this semiequilibrium model successfully reproduced variations of MALDI signal intensities AH(+) and MH+ with two parameters: the fraction of ionized matrix a <= 10(-5) and an effective temperature T = 1200 and 1100 K for Phe/DHB and Ala/DHB systems, respectively. These values show good agreement with those determined previously by different experimental approaches. The extent of thermal equilibrium was determined to be 95% and 98% for Phe/DHB and Ala/DHB systems, respectively, suggesting that the proton transfer reactions almost proceed to their thermal equilibrium.

Infrared spectra of two isomers of protonated carbonyl sulfide (HOCS+ and HSCO+) and t-HOCS in solid para-hydrogen
Masashi Tsuge, Yuan-Pern Lee
The Journal of Chemical Physics, 145, 16, 164308, 164308, {AIP} Publishing, 28 Oct. 2016, [Peer-reviewed], [Lead author, Corresponding author]
English, Scientific journal, We report infrared (IR) spectra of HOCS+, HSCO+, t-HOCS, and other species produced on electron bombardment of a mixture of carbonyl sulfide (OCS) and para-hydrogen (p-H-2) during deposition at 3.2 K. After maintenance of the matrix in darkness for 15 h, the intensities of absorption features of HOCS+ at 2945.9 (nu(1)), 1875.3 (nu(2)), and 1041.9 (nu(3)) cm(-1) and those of HSCO+ at 2506.9 (nu(1)) and 2074.2 (nu(2)) cm(-1) decreased through neutralization with trapped electrons. Lines observed at 3563.4, 1394.8, and 1199.0 cm(-1), which decreased slightly in intensity after maintenance in darkness and were nearly depleted after irradiation at 373 nm, are assigned to a t-HOCS radical. The corresponding spectra of their C-13- and D-isotopologues were observed. The IR spectra of HSCO+ and t-HOCS and those of modes nu(2) and nu(3) of HOCS+ are new. The assignments were made according to the expected chemical behavior and a comparison of experimental and calculated wavenumbers and C-13- and D-isotopic shifts. The wavenumber of the OH stretching mode (2945.9 cm(-1)) of HOCS+ in solid p-H-2 is significantly red-shifted from that (3435.16 cm(-1)) reported for gaseous HOCS+; this shift is attributed to partial sharing of a proton between OCS and H-2. The corresponding p-H-2 induced shift is small in HSCO+ because of a much weaker interaction between HSCO+ and H-2. Published by AIP Publishing.

Infrared spectra of ovalene (C32H14) and hydrogenated ovalene (C32H15˙) in solid para-hydrogen
Masashi Tsuge
Physical Chemistry Chemical Physics, 18, 41, 28864, 28871, ROYAL SOC CHEMISTRY, 22 Sep. 2016, [Peer-reviewed], [Lead author, Corresponding author]
English, Scientific journal, We report the infrared (IR) spectra of ovalene (C32H14) and hydrogenated ovalene (C32H15 center dot) in solid para-hydrogen (p-H-2). The hydrogenated ovalene and protonated ovalene were generated from electron bombardment of a mixture of ovalene and p-H-2 during deposition of a matrix at 3.2 K. The features that decreased with time have been previously assigned to 7-C32H15+, the most stable isomer of protonated ovalene (Astrophys. J., 2016, 825, 96). The spectral features that increased with time are assigned to the most stable isomer of hydrogenated ovalene (7-C32H15 center dot) based on the expected chemistry and on a comparison with the vibrational wavenumbers and IR intensities predicted by the B3PW91/6-311++ G(2d, 2p) method. The mechanism of formation of 7-C32H15 center dot is discussed according to the observed changes in intensity and calculated energetics of possible reactions of H + C32H14 and isomerization of C32H15 center dot. The formation of 7-C32H15 center dot is dominated by the reaction H + C32H14 -> 7-C32H15 center dot, implying that, regardless of the presence of a barrier, the hydrogenation of polycyclic aromatic hydrocarbons occurs even at 3.2 K.

Infrared absorption of t-HOCO+, H+(CO2)2, and HCO2− produced in electron bombardment of CO2 in solid para-H2
Prasanta Das, Masashi Tsuge, Yuan-Pern Lee
The Journal of Chemical Physics, 145, 1, 014306, 014306, {AIP} Publishing, 07 Jul. 2016, [Peer-reviewed]
English, Scientific journal, We have employed electron bombardment during matrix deposition of CO2 (or (CO2)-C-13, (CO2)-O-18) and para-hydrogen (p-H-2) at 3.2 K and recorded infrared (IR) spectra of t-HOCO+, H+(CO2)(2) , HCO2-, CO2-, t-HOCO, and other species isolated in solid p-H-2. After the matrix was maintained in darkness for 13 h, intensities of absorption features of t-HOCO+ at 2403.5 (v(1)), 2369.9 (v(2)), 1018.1 (v(4)), and 606.5 (v(6)) cm(-1) and those of H+(CO2)(2) at 1341.1, 883.6, and 591.5 cm(-1) decreased. Corresponding lines of isotopologues were observed when (CO2)-C-13 or (CO2)-O-18 replaced CO2. In contrast, lines of HCO2- at 2522.4 (v(1)), 1616.1 (v(5)), 1327.9 (v(2)), and 745.6 (v(3)) cm(-1) increased in intensity; corresponding lines of (HCO2-)-C-13 or (HCO2-)-O-18 were also observed. Lines of t-DOCO+ and DCO2- were observed in an electron bombarded CO2/normal-deuterium (n-D-2) matrix. Data of v(6) of t-HOCO+ and all observed modes of (HOCO+)-O-18-O-18 and (HCO2-)-O-18 are new. The assignments were made according to expected chemical behavior, observed isotopic shifts, and comparisons with vibrational wavenumbers and relative intensities of previous reports and calculations with the B3PW91/aug-cc-pVQZ method. The v(1) line of t-HOCO+ in solid p-H-2 (2403.5 cm(-1)), similar to the line at 2673 cm(-1) of t-HOCO+ tagged with an Ar atom, is significantly red-shifted from that reported for gaseous t-HOCO+ (3375.37 cm(-1)) due to partial proton sharing between CO2 and H-2 or Ar. The v(1) line of HCO2- in solid p-H-2 (2522.4 cm(-1)) is blue shifted from that reported for HCO2- in solid Ne (2455.7 cm(-1)) and that of HCO2- tagged with Ar (2449 cm(-1)); this can be explained by the varied solvation effects by Ne, Ar, or H-2 on the mixing of H+ + CO2 and H+ CO2- surfaces. Possible formation mechanisms of t-HOCO+, H+(CO2)(2), HCO2-, CO2-, t-HOCO, H2O, and t-HCOOH are discussed. Published by AIP Publishing.

THE INFRARED SPECTRUM OF PROTONATED OVALENE IN SOLID PARA-HYDROGEN AND ITS POSSIBLE CONTRIBUTION TO INTERSTELLAR UNIDENTIFIED INFRARED EMISSION
Masashi Tsuge
The Astrophysical Journal, 825, 2, 96, IOP PUBLISHING LTD, 06 Jul. 2016, [Peer-reviewed], [Lead author, Corresponding author]
English, Scientific journal, The mid-infrared emission from galactic objects, including reflection nebulae, planetary nebulae, proto-planetary nebulae, molecular clouds, etc, as well as external galaxies, is dominated by the unidentified infrared (UIR) emission bands. Large protonated polycyclic aromatic hydrocarbons (H(+)PAHs) were proposed as possible carriers, but no spectrum of an H(+)PAH has been shown to exactly match the UIR bands. Here, we report the IR spectrum of protonated ovalene (7-C32H15+) measured in a para-hydrogen (p-H-2) matrix at 3.2 K, generated by bombarding a mixture of ovalene and p-H-2 with electrons during matrix deposition. Spectral assignments were made based on the expected chemistry and on the spectra simulated with the wavenumbers and infrared intensities predicted with the B3PW91/6-311++G(2d, 2p) method. The close resemblance of the observed spectral pattern to that of the UIR bands suggests that protonated ovalene may contribute to the UIR emission, particularly from objects that emit Class A spectra, such as the IRIS reflection nebula, NGC 7023.

Infrared Spectrum of Toluene: Comparison of Anharmonic Isolated-Molecule Calculations and Experiments in Liquid Phase and in a Ne Matrix
Masashi Tsuge
JOURNAL OF PHYSICAL CHEMISTRY A, 120, 19, 3380, 3389, AMER CHEMICAL SOC, 26 Apr. 2016, [Peer-reviewed], [International Magazine]
English, Scientific journal, First-principles anharmonic calculations are carried out for the CH stretching vibrations of isolated toluene and compared with the experimental infrared spectra of isotopologues of toluene in a Ne matrix at 3 K and of liquid toluene at room temperature. The calculations use the vibrational self-consistent field method and the B3LYP potential surface. In general, good agreement is found between the calculations and experiments. However, the spectrum of toluene in a Ne matrix is more complicated than that predicted theoretically. This distinction is discussed in terms of matrix-site and resonance effects. Interestingly, the strongest peak in the CH stretching spectrum has similar widths in the liquid phase and in a Ne matrix, despite the very different temperatures. Implications of this observation to the broadening mechanism are discussed. Finally, our results show that the B3LYP potential offers a good description of the anharmonic CH stretching band in toluene, but a proper description of matrix-site and resonance effects remains a challenge.

Complex refractive index of secondary organic aerosol generated from isoprene/NOx photooxidation in the presence and absence of SO2
Tomoki Nakayama, Kei Sato, Masashi Tsuge, Takashi Imamura, Yutaka Matsumi
Journal of Geophysical Research, 120, 15, 7777, 7787, Wiley-Blackwell, 15 Jul. 2015, [Peer-reviewed]
English, Scientific journal, We report the firstmeasurements of the complex refractive index (RI) at 375, 405, 532, and 781 nm for secondary organic aerosol (SOA) generated from isoprene/NOx photooxidation. At all wavelengths studied, slightly greater real components of the RI were observed for the SOA generated in the absence of SO2 compared with those generated in its presence. Considering the chemical properties, the differences in the oxidation state and/or ratio of particle density to molecular weight of compounds in the SOA are considered to be the main factors determining the real components. The imaginary components at ≤532 nm were found to increase with increasing initial SO2 concentration. The highly conjugated oligomers are suggested to be plausible chromophore candidates. This study suggests that when large amounts of SOA are generated after mixing of isoprene with NOx and SOx, light absorption of these SOAs may compete with that of black carbon, especially at ultraviolet wavelengths.

Experimental and theoretical study of the HXeI⋯HCl and HXeI⋯HCCH complexes
Zhu, C., Tsuge, M., R{\"a}s{\"a}nen, M., Khriachtchev, L.
Journal of Chemical Physics, 142, 14, 144306, AMER INST PHYSICS, 13 Apr. 2015, [Peer-reviewed]
English, Scientific journal, The HXeI center dot center dot center dot HCl and HXeI center dot center dot center dot HCCH complexes are studied computationally and experimentally in a Xe matrix. In the experiments, three bands of the HXeI center dot center dot center dot HCl complex and one band of the HXeI center dot center dot center dot HCCH complex in the H-Xe stretching region are observed. The monomer-to-complex shifts are + 94, + 111, and + 155 cm(-1) for the HXeI center dot center dot center dot HCl complex and + 49 cm(-1) for the HXeI center dot center dot center dot HCCH complex. The bands of the complexed HCl molecules are also observed with large red shifts from the HCl monomer (-187, -252, and -337 cm(-1)). The ab initio calculations at the CCSD(T)/def2-TZVPPD level of theory predict two stable structures for the HXeI center dot center dot center dot HCl complex with interaction energies of -3.72 and -0.28 kcal mol(-1) and one structure for the HXeI center dot center dot center dot HCCH complex with an interaction energy of -2.67 kcal mol(-1) and the calculated monomer-to-complex shifts are in a good agreement with experiment (in the case of HXeI center dot center dot center dot HCl, for the stronger structure). The HXeI molecules are decomposed by broad-band infrared light; however, the decomposition is much more efficient for the HXeI monomer than for the complexes studied here as well as for the previously studied HXeI center dot center dot center dot HI and HXeI center dot center dot center dot HBr complexes. In fact, the decomposition efficiency decreases as the monomer-to-complex shift of the H-Xe stretching mode increases. (C) 2015 AIP Publishing LLC.

Tunneling isomerization of small carboxylic acids and their complexes in solid matrixes: A computational insight
Tsuge, M., Khriachtchev, L.
Journal of Physical Chemistry A, 119, 11, 2628, 2635, AMER CHEMICAL SOC, 01 Mar. 2015, [Peer-reviewed], [Lead author, Corresponding author]
English, Scientific journal, We have studied hydrogen-atom tunneling in the cis-to-trans conformational change of some carboxylic acid monomers and formic acid (FA) complexes and dimers at the MP2(full) and CCSD(T) levels of theory within the Wentzel-Kramers-Brillouin approximation. The barrier for the minimum energy path, where the OH bond length and the COH bending angle are optimized, is found to be a good approximation for providing the highest barrier transparency. The matrix effect on the transmission coefficients of cis-FA monomer, trans-cis FA dimer (tc1), and cis-acetic acid monomer are modeled by the polarizable continuum model (PCM) at the MP2(full) level of theory in different environments. For the cis-FA monomer and trans-cis FA dimer (tc1), the calculated transmission coefficients agree with the experimental lifetimes observed in noble-gas solids. However, this method cannot reproduce the experimental results obtained for cis-acetic acid. Moreover, the long lifetime of cis-FA and cis-acetic acid in the N-2 environment cannot be reproduced either, which is most probably due to specific interactions that are not included in the PCM. The calculation for cis-HCOOD shows a strong decrease of the barrier transparency compared to that for cis-HCOOH, which is consistent with the experiments. In general, good agreement is observed between the calculated barrier transparency (including PCM) and experimental tunneling rate. However, some exceptions are found, which shows that additional factors influence the tunneling rate.

Near-infrared femtosecond laser ionization of the acetic acid dimer
Amada, M., Sato, Y., Tsuge, M., Hoshina, K.
Chemical Physics Letters, 624, 24, 28, ELSEVIER SCIENCE BV, 11 Feb. 2015, [Peer-reviewed]
English, Scientific journal, Fragment ions produced after the ionization of the acetic acid dimer (CH3COOH)(2) in a near-infrared intense femtosecond laser field were measured using time-of-flight mass spectrometry. The two-body Coulomb explosion (CE) process (CH3COOH)(2)(2+) -> 2CH(3)COOH(+) with a kinetic energy release of 3.4 eV, similar to the case of (HCOOH)(2)(2+) (Hoshina et al., 2012), was identified. The two-body CE of (CH3COOH)(2)(2+) was induced when the laser polarization direction was perpendicular to the C center dot center dot center dot C intermolecular axisin contrast to the case of (HCOOH)(2)(2+). The preferential configurations may be those that deform dimer structures close to dimer dications during the double-ionization process. (C) 2015 Elsevier B.V. All rights reserved.

HXeI and HXeH in Ar, Kr, and Xe matrices: Experiment and simulation
Zhu, C., Niimi, K., Taketsugu, T., Tsuge, M., Nakayama, A., Khriachtchev, L.
Journal of Chemical Physics, 142, 5, 54305, AMER INST PHYSICS, 04 Feb. 2015, [Peer-reviewed]
English, Scientific journal, Experimental and theoretical studies of HXeI and HXeH molecules in Ar, Kr, and Xe matrices are presented. HXeI exhibits the H-Xe stretching bands at 1238.0 and 1239.0 cm(-1) in Ar and Kr matrices, respectively, that are blue-shifted from the HXeI band observed in a Xe matrix (1193 cm(-1)) by 45 and 46 cm(-1). These shifts are larger than those observed previously for HXeCl (27 and 16 cm(-1)) and HXeBr (37 and 23 cm(-1)); thus, the matrix effect is stronger for less stable molecules. The results for HXeI are qualitatively different from all previous results on noble-gas hydrides with respect to the frequency order between Ar and Kr matrices. For previously studied HXeCl, HXeBr, and HXeCCH, the H-Xe stretching frequency is reliably (by > 10 cm(-1)) higher in an Ar matrix than in a Kr matrix. In contrast, the H-Xe stretching frequency of HXeI in an Ar matrix is slightly lower than that in a Kr matrix. HXeH absorbs in Ar and Kr matrices at 1203.2 and 1192.1 cm(-1) (the stronger band for a Kr matrix), respectively. These bands are blue-shifted from the stronger band of HXeH in a Xe matrix (1166 cm(-1)) by 37 and 26 cm(-1), and this frequency order is the same as observed for HXeCl, HXeBr, and HXeCCH but different from HXeI. The present hybrid quantum-classical simulations successfully describe the main experimental findings. For HXeI in the < 110 > (double substitution) site, the order of the H-Xe stretching frequencies (nu(Xe) < nu(Ar) < nu(Kr)) is in accord with the experimental observations, and also the frequency shifts in Ar and Kr matrices from a Xe matrix are well predicted (30 and 34 cm(-1)). Both in the theory and experiment, the order of the H-Xe stretching frequencies differs from the case of HXeCl, which suggests the adequate theoretical description of the matrix effect. For HXeH in the < 100 > (single substitution) site, the order of the frequencies is nu(Xe) < nu(Kr) < nu(Ar), which also agrees with the experiments. The calculated frequency shifts for HXeH in Ar and Kr matrices with respect to a Xe matrix (36 and 23 cm(-1)) are in a good agreement with the experiments. The present calculations predict an increase of the H-Xe stretching frequencies in the noble-gas matrices with respect to vacuum. (C) 2015 AIP Publishing LLC.

Infrared identification of proton-bound rare-gas dimers (XeHXe)+, (KrHKr)+, and (KrHXe)+ and their deuterated species in solid hydrogen
Tsuge, M., Kalinowski, J., Gerber, R.B., Lee, Y.-P.
Journal of Physical Chemistry A, 119, 11, 2651, 2660, AMER CHEMICAL SOC, 2015, [Peer-reviewed], [Lead author]
English, Scientific journal, Proton-bound rare-gas dimer (RgHRg)(+), in which Rg represents a rare-gas atom, serves as a prototypical system for proton solvation by inert-gas atoms. Until now, only centrosymmetric species with Rg = Ar, Kr, or Xe have been identified with infrared spectra. We employed electron bombardment during deposition of a mixture of Xe (or Kr) in p-H-2 at 3.2 K to prepare (RgHRg)(+). Lines at 847.0 and 972.1 cm(-1) are assigned as the Rg-H-Rg antisymmetric stretching (nu(3)) mode and its combination with the RgHRg symmetric stretching (nu(1) + nu(3)) mode of (XeHXe)(+) in solid p-H-2, respectively. Lines at 871.1 and 974.0 cm(-1) are assigned as the nu(3) and nu(1) + nu(3) modes of (KrHKr)(+) in solid p-H-2, respectively. Slightly shifted and broadened lines were observed for these species in solid n-H-2. These results agree satisfactorily with reported experimental values of (XeHXe)(+) and (KrHKr)(+) in solid Xe, Kr, and Ar, and with the quantum-chemically predicted anharmonic vibrational wavenumbers of these species in the gaseous phase; the significant spectral shifts in various matrixes are rationalized with the proton affinities of the hosts. When a mixture of Xe and Kr in p-H-2 was used, an additional broad feature at 1284 cm(-1) was observed and assigned as the nu(3) mode of (KrHXe)(+) in solid p-H-2. This line shifted to 1280 cm(-1) in solid n-H-2 and the corresponding line of (KrDXe)(+) was observed at 954 cm(-1) in n-D-2. The observations of these lines are new; the wavenumbers significantly blue shifted from those of the centrosymmetric (RgHRg)(+) agree with the quantum-chemically predicted anharmonic vibrational wavenumbers of 1279 cm(-1) for (KrHXe)(+) and 916 cm(-1) for (KrDXe)(+). Analysis of the computational results shows that electronic correlation effects play a much greater role for the asymmetric than for the symmetric species. An interpretation for this is provided.

Matrix-isolation and computational study of the HXeY⋯H2O complexes (Y = Cl, Br, and I)
Tsuge, M., Berski, S., R{\"a}s{\"a}nen, M., Latajka, Z., Khriachtchev, L.
Journal of Chemical Physics, 140, 4, 44323, AMER INST PHYSICS, 30 Jan. 2014, [Peer-reviewed], [Lead author, Corresponding author]
English, Scientific journal, The HXeY center dot center dot center dot H2O complexes (Y = Cl, Br, and I) are studied theoretically and experimentally. The calculations at the CCSD(T)/def2-TZVPPD level of theory predict two stable structures for Y = Cl and Br and one structure for Y = I, with interaction energies up to about -7 kcal mol(-1). In the experiments, we have identified several infrared absorption bands originating from the H-Xe stretching mode of these complexes in a xenon matrix. The monomer-to-complex frequency shifts of this mode are up to +82 cm(-1) (Y = Cl), +101 cm(-1) (Y = Br), and +138 cm(-1) (Y = I), i.e., the shift is smaller for more strongly bound molecules. Based on the agreement of the experimental and theoretical results, the observed bands are assigned to the most stable planar structure with an O-H center dot center dot center dot Y-Xe hydrogen bond. (C) 2014 AIP Publishing LLC.

Modeling of HXeBr in CO2 and Xe environments: Structure, energetics and vibrational spectra
Cohen, A., Tsuge, M., Khriachtchev, L., R{\"a}s{\"a}nen, M., Gerber, R.B.
Chemical Physics Letters, 594, 18, 22, ELSEVIER SCIENCE BV, 22 Jan. 2014, [Peer-reviewed]
English, Scientific journal, HXeBr in CO2 and Xe environments is modeled at the B3LYP-D level of theory, using a full single shell of CO2 molecules and Xe atoms around the HXeBr molecule. For the CO2 environment, the optimized structure indicates a double substitutional site in the otherwise approximately preserved structure of solid CO2. The calculated vibrational spectra and energetic properties indicate strong interactions of HXeBr with the CO2 environment, which is significantly stronger than in the case of the Xe environment. The H-Xe stretching frequency obtained by a variant of the anharmonic VSCF method is in good accord with the available experimental data. (C) 2014 Elsevier B.V. All rights reserved.

Matrix-Isolation FTIR Studies of Molecular Complexes
TSUGE MASASHI
分光研究, 62, 6, 268, 275, 日本分光学会, 15 Dec. 2013, [Peer-reviewed], [Invited], [Lead author, Corresponding author]
Japanese, Scientific journal

Environmental effects on noble-gas hydrides: HXeBr, HXeCCH, and HXeH in noble-gas and molecular matrices
Tsuge, M., Lignell, A., R{\"a}s{\"a}nen, M., Khriachtchev, L.
Journal of Chemical Physics, 139, 20, 204303, AMER INST PHYSICS, 22 Nov. 2013, [Peer-reviewed], [Lead author, Corresponding author]
English, Scientific journal, Noble-gas hydrides HNgY (Ng is a noble-gas atom and Y is an electronegative group) are sensitive probes of local environment due to their relatively weak bonding and large dipole moments. We experimentally studied HXeBr in Ar, Kr, and N-2 matrices, HXeCCH in Ne and N-2 matrices, and HXeH in an N-2 matrix. These are the first observations of noble-gas hydrides in an N-2 matrix. An N-2 matrix strongly increases the H-Xe stretching frequency of HXeBr and HXeCCH with respect to a Ne matrix, which is presumably due to a strong interaction between the HNgY dipole moment and quadrupole moments of the surrounding lattice N-2 molecules. The spectral shift of HXeBr in an N-2 matrix is similar to that in a CO2 matrix, which is a rather unexpected result because the quadrupole moment of CO2 is about three times as large as that of N-2. The H-Xe stretching frequencies of HXeBr and HXeCCH in noble-gas matrices show a trend of v(Ne) < v(Xe) < v(Kr) < v(Ar), which is a non-monotonous function of the dielectric constants of the noble-gas solids. The MP2(full) calculations of HXeBr and HXeCCH with the polarizable continuum model as well as the CCSD(T) calculations of the HXeBr . . . Ng and HXeCCH . . . Ng (Ng = Ne, Ar, Kr, and Xe) complexes cannot fully explain the experimental observations. It is concluded that more sophisticated computational models should be used to describe these experimental findings. (C) 2013 AIP Publishing LLC.

Photochemistry of the ozone-water complex in cryogenic neon, argon, and krypton matrixes
Tsuge, M., Tsuji, K., Kawai, A., Shibuya, K.
Journal of Physical Chemistry A, 117, 49, 13105, 13111, AMER CHEMICAL SOC, 19 Nov. 2013, [Peer-reviewed], [Lead author, Corresponding author]
English, Scientific journal, The photochemistry of ozone water complexes and the wavelength dependence of the reactions were studied by matrix isolation FTIR spectrometry in neon, argon, and krypton matrixes. Hydrogen peroxide was formed upon the irradiation of UV light below 355 nm. Quantitative analyses of the reactant and product were performed to evaluate the matrix cage effect of the photoreaction. In argon and krypton matrixes, a bimolecular O(D-1) + H2O -> H2O2 reaction was found to occur to form hydrogen peroxide, where the O(D-1) atom generated by the photolysis of ozone diffused in the cryogenic solids to encounter water. In a neon matrix, hydrogen peroxide was generated through intracage photoreaction of the ozone water complex, indicating that a neon matrix medium is most appropriate to study the Photochemistry of the ozone water complex.

Experimental and computational study of the HXe⋯IHY complexes (Y = Br and I)
Tsuge, M., Berski, S., R{\"a}s{\"a}nen, M., Latajka, Z., Khriachtchev, L.
Journal of Chemical Physics, 138, 10, 104314, AMER INST PHYSICS, 13 Mar. 2013, [Peer-reviewed], [Lead author, Corresponding author]
English, Scientific journal, The complexes of HXeI with hydrogen halides HY (Y = Br and I) are studied computationally and experimentally in a xenon matrix. The calculations at the CCSD(T)/def2-TZVPPD level of theory predict several energy minima for the HXeI center dot center dot center dot HY complexes with interaction energies from -4.69 to -0.23 kcal mol(-1). We have identified three bands of the HXeI center dot center dot center dot HI complexes in the H-Xe stretching region with the monomer-to-complex blue shifts from +37 to +96 cm(-1), and three bands of the HXeI center dot center dot center dot HBr complexes with blue shifts from +88 to +157 cm(-1). The structural assignments are done on the basis of the strong H-Xe and HY stretching bands and the decomposition rates upon broadband IR irradiation. The experimental bands with larger shifts are assigned to the most stable structures of the HXeI center dot center dot center dot HY complexes with the Y-H center dot center dot center dot I hydrogen bond. c 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4794309]

Infrared characterization of the HCOOH•••CO 2 complexes in solid argon: Stabilization of the higher-energy conformer of formic acid
Tsuge, M., Marushkevich, K., R{\"a}s{\"a}nen, M., Khriachtchev, L.
Journal of Physical Chemistry A, 116, 22, 5305, 5311, AMER CHEMICAL SOC, 07 May 2012, [Peer-reviewed], [Lead author, Corresponding author]
English, Scientific journal, The complexes of formic acid (HCOOH, FA) with carbon dioxide are studied by infrared spectroscopy in an argon matrix. Two trans-FA center dot center dot center dot CO2 and one cis-FA center dot center dot center dot CO2 complexes are experimentally identified while the calculations at the MP2(full)/6-311++G(2d,2p) level of theory predict one more minimum for the cis-FA center dot center dot center dot CO2 complex. The complex of the higher-energy conformer cis-FA with CO2 is prepared by vibrational excitation of the ground-state trans-FA conformer combined with thermal annealing. The lifetime of the cis-FA center dot center dot center dot CO2 complex in an argon matrix at 10 K is 2 orders of magnitude longer than that of the cis-FA monomer. This big difference is explained by the computational results which show a higher stabilization barrier for the complex. The solvation effects in solid argon are theoretically estimated and their contribution to the stabilization barriers of the higher-energy species is discussed. The relative barrier transmissions for hydrogen tunneling in the cis-FA center dot center dot center dot CO2 complex and cis-FA monomer are in good agreement with the experimental decay rates.

High kinetic stability of HXeBr upon interaction with carbon dioxide: HXeBr·CO 2 complex in a xenon matrix and HXeBr in a carbon dioxide matrix
Tsuge, M., Berski, S., Stachowski, R., R{\"a}s{\"a}nen, M., Latajka, Z., Khriachtchev, L.
Journal of Physical Chemistry A, 116, 18, 4510, 4517, AMER CHEMICAL SOC, 11 Apr. 2012, [Peer-reviewed], [Lead author]
English, Scientific journal, We investigate the conditions when noble-gas hydrides can be found in real environments and report on the preparation and identification of the HXeBr center dot center dot center dot CO2 complex in a xenon matrix and HXeBr in a carbon dioxide matrix. The H-Xe stretching mode of the HXeBr center dot center dot center dot CO2 complex in a xenon matrix is observed at 1557 cm(-1), showing a spectral shift of +53 cm(-1) from the HXeBr monomer. The calculations at the CCSD(T)/aug-cc-pVTZ-PP(Xe,Br) level of theory give two stable structures for the HXeBr center dot center dot center dot CO2 complex with frequency shifts of +55 and +103 cm(-1), respectively. On the basis of the calculations, the experimentally observed band is assigned to the more stable structure with a "parallel" geometry. The HXeBr molecule was prepared in a carbon dioxide matrix and has the H-Xe stretching frequency of 1646 cm(-1), meaning a strong matrix shift and stabilization of the H-Xe bond. The deuterated species DXeBr in a carbon dioxide matrix absorbs at 1200 cm(-1). This is the first case where a noble-gas hydride is prepared in a molecular solid. The thermal stabilities of HXeBr and HXeBr center dot center dot center dot CO2 complex in a xenon matrix and HXeBr in a carbon dioxide matrix were examined. We have found a high thermal stability of HXeBr in carbon dioxide ice (at least up to 100 K), i.e., under conditions that may occur in nature.

Double ionization and coulomb explosion of the formic acid dimer by intense near-infrared femtosecond laser pulses
Hoshina, K., Hagihara, H., Tsuge, M.
Journal of Physical Chemistry A, 116, 2, 826, 831, AMER CHEMICAL SOC, 2012, [Peer-reviewed]
English, Scientific journal, Ionization and fragmentation of formic acid dimers (HCOOH)(2) and (DCOOD)(2) by irradiation of femtosecond laser pulses (100 fs, 800 nm, similar to 1 x 10(14) W/cm(2)) were investigated by time-of-flight (TOF) mass spectrometry. In the TOF spectra, we observed fragment ions (HCOOH)H+, (HCOOH)- HCOO+, and H3O+, which were produced via the dissociative ionization of (HCOOH)(2). In addition, we found that the TOF signals of COO+, HCOO+, and HCOOH+ have small but clear side peaks, indicating fragmentation with large kinetic energy release caused by Coulomb explosion. On the basis of the momentum matching among pairs of the side peaks, a Coulomb explosion pathway of the dimer dication, (HCOOH)(2)(2+) -> HCOOH+ + HCOOH+, was identified with the total kinetic energy release of 3.6 eV. Quantum chemical calculations for energies of (HCOOH)(2)(2+) were also performed, and the kinetic energy release of the metastable dication was estimated to be 3.40 eV, showing good agreement with the observation. COO+ and HCOO+ signals with kinetic energies of 1.4 eV were tentatively assigned to be fragment ions through Coulomb explosion occurring after the elimination of a hydrogen atom or molecule from (HCOOH)(2)(2+). The present observation demonstrated that the formic acid dimer could be doubly ionized prior to hydrogen bond breaking by intense femtosecond laser fields.

Metastable decomposition and hydrogen migration of ethane dication produced in an intense femtosecond near-infrared laser field
Hoshina, K., Kawamura, H., Tsuge, M., Tamiya, M., Ishiguro, M.
Journal of Chemical Physics, 134, 6, 64324, AMER INST PHYSICS, 14 Feb. 2011, [Peer-reviewed]
English, Scientific journal, We investigated a formation channel of triatomic molecular hydrogen ions from ethane dication induced by irradiation of intense laser fields (800 nm, 100 fs, similar to 1 x 10(14) W/cm(2)) by using time of flight mass spectrometry. Hydrogen ion and molecular hydrogen ion (H,D)(n)+ (n = 1-3) ejected from ethane dications, produced by double ionization of three types of samples, CH(3)CH(3), CD(3)CD(3), and CH(3)CD(3), were measured. All fragments were found to comprise components with a kinetic energy of similar to 3.5 eV originating from a two-body Coulomb explosion of ethane dications. Based on the signal intensities and the anisotropy of the ejection direction with respect to the laser polarization direction, the branching ratios, H(+):D(+) = 66:34, H(2)(+):HD(+):D(2)(+) = 63:6:31, and H(3)(+):H(2)D(+): HD(2)(+):D(3)(+) = 26:31:34: 9 for the decomposition of C(2)H(3)D(3)(2+), were determined. The ratio of hydrogen molecules, H(2):HD:D(2) = 31:48:21, was also estimated from the signal intensities of the counter ion C(2)(H,D)(4)(2+). The similarity in the extent of H/D mixture in (H,D)(3)(+) with that of (H,D)(2) suggests that these two dissociation channels have a common precursor with the C(2)H(4)(2+)center dot center dot center dot H(2) complex structure, as proposed theoretically in the case of H3+ ejection from allene dication [A. M. Mebel and A. D. Bandrauk, J. Chem. Phys. 129, 224311 (2008)]. In contrast, the (H,D)(2)(+) ejection path with a lower extent of H/D mixture and a large anisotropy is expected to proceed essentially via a different path with a much rapid decomposition rate. For the Coulomb explosion path of C-C bond breaking, the yield ratios of two channels, CH(3)CD(3)(2+) -> CH(3)(+) + CD(3)(+) and CH(2)D(+) + CHD(2)(+), were 81:19 and 92:8 for the perpendicular and parallel directions, respectively. This indicates that the process occurs at a rapid rate, which is comparable to hydrogen migration through the C-C bond, resulting in smaller anisotropy for the latter channel that needs H/D exchange. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3549137]

Effect of esterification on MALDI-MS detection sensitivity for amino acids
Tsuge, M., Hoshina, K.
International Journal of Mass Spectrometry, 300, 1, 39, 43, ELSEVIER SCIENCE BV, 2011, [Peer-reviewed], [Lead author]
English, Scientific journal, Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) spectra for methyl esters H-X-OMe of 11 amino acid X were measured at various analyte/matrix mixing ratios using alpha-cyano-4-hydroxycinnamic acid (CHCA) matrix. For each amino acid, the effect of esterification on MALDI signals was examined by comparing the signal intensity ratio (H-X-OMe)H(+)/(CHCA)H(+) for the ester H-X-OMe with the comparable ratio XH(+)/(CHCA)H(+) for the corresponding amino acid X. For all 11 amino acids, the ratios for the esters are in line with a thermal equilibrium model [M. Tsuge, K. Hoshina, Investigation of protonation efficiency for amino acids in matrix-assisted laser desorption/ionization, Bull. Chem. Soc. Jpn. 83 (2010), 1188-1192.]. For 9 of the amino acids - Ala, Arg, Gly, Ile, Leu, Phe, Set. Trp, and Val - the ratio for the amino acid agrees with the ratio for the ester, within the standard error. For the other 2 amino acids - His and Lys - the ratio for the amino acid is exceptionally smaller than the ratio for the ester, indicating that the effect of esterification is significant. This compensation by esterification suggests that for His/CHCA and Lys/CHCA systems, the coexistence of a carboxyl group and a basic side chain are responsible for suppression in the formation of HisH(+) and LysH(+), possibly by reducing the amount of desorbed analyte and/or decreasing the effective gas-phase basicity (GB) in the MALDI plume. (C) 2010 Elsevier B.V. All rights reserved.

Investigation of protonation efficiency for amino acids in matrix-assisted laser desorption/ionization
Tsuge, M., Hoshina, K.
Bulletin of the Chemical Society of Japan, 83, 10, 1188, 1192, CHEMICAL SOC JAPAN, 05 Oct. 2010, [Peer-reviewed], [Lead author]
English, Scientific journal, MALDI spectra for 20 natural amino acids were measured at various mixing ratios of amino acid (A) and matrix (M: CHCA or DHB) to clarify the main protonation process as well as MALDI plume conditions, which affect the detection sensitivity of analytes in MALDI. Signal intensities of protonated amino acids (AH(+)) relative to protonated matrix (MH+), obtained as AH(+)/MH+, revealed a clear correlation between AH(+)/MH+ and the gas-phase basicity (GB) of the respective amino acids except for three basic amino acids, Lys, His, and Arg. This relationship between AH(+)/MH+ and GB was interpreted in terms of a protonation model in which AH+ is produced through a reversible proton-transfer reaction of MH+ + A reversible arrow M + AH(+) reaching thermal equilibrium in the MALDI plume. The GB of matrix molecules and MALDI plume temperatures independently determined from analysis of the present data (851 kJ mol(-1) and 1510 K for CHCA and 830 kJ mol(-1) and 1330K for DHB) agreed well with values in the literature, indicating the validity of the present interpretation. The ratios AH(+)/MH+ for Lys, His, and Arg had lower values than those expected from the GB by a factor of 10(-1)-10(-2). This discrepancy could have been caused by proton acceptance by amino groups in amino acids, which are caused by an intramolecular hydrogen bond, determine the magnitude of the GB for basic amino acids.

Formation of H3O+ from ethanol clusters induced by intense femtosecond laser fields
K. Hoshina, M. Tsuge
Chemical Physics Letters, 489, 4-6, 154, 158, Elsevier BV, 03 Mar. 2010, [Peer-reviewed]
English, Scientific journal

Formation of H3O+ from alcohols and ethers induced by intense laser fields
Shirota, T., Mano, N., Tsuge, M., Hoshina, K.
Rapid Communications in Mass Spectrometry, 24, 5, 679, 686, JOHN WILEY & SONS LTD, 12 Feb. 2010, [Peer-reviewed]
English, Scientific journal, The processes of H(3)O(+) production from alcohols (ethanol, 2-propanol, 1-propanol, 2-butanol) and ethers (diethyl ether and ethyl methyl ether), and their deuterium-substituted species, by intense laser fields (800 nm, 100 fs, similar to 1 x 10(14) W/cm) were investigated through time-of-flight (TOF) mass spectrometry. H(3)O(+) formation was observed for all these compounds except for ethyl methyl ether. From the analysis of TOF signals of H((3-n))D(n)O(+) (n = 0, 1, 2, and 3) that have expanding tails with increasing flight time, it has been confirmed that the reaction proceeds through metastable dissociation from the intermediate species C(2)H((5-m))D(m)O(+) (m = 0-5). The common shape of the H((3-n))D(n)O(+) signal profiles contains two major distributions in the time constant, i.e., fast and slow components of <50 ns and similar to 500 ns, respectively. The H((3-n))D(n)O(+) branching ratio is interpreted to be the result of complete scrambling of four hydrogen atoms at the C-C site in C(2)H(4)-OH(+), and partial exchange (18-38%) of a hydrogen atom in the OH group with four other hydrogen atoms within 1 ns prior to H((3-n))D(n)O(+) production. Ab initio calculations for the isomers and transition states Of C(2)H(5)O(+) were also performed, and the observed H((3-n))D(n)O(+) production mechanism has been discussed. In addition, a stable isomer having a complex structure and two isomerization pathways were discovered to contribute to the H(3)O(+) formation process. Copyright (C) 2010 John Wiley & Sons, Ltd.

Infrared spectroscopy of ozone-water complex in a neon matrix
Tsuge, M., Tsuji, K., Kawai, A., Shibuya, K.
Journal of Physical Chemistry A, 111, 18, 3540, 3547, AMER CHEMICAL SOC, 19 Apr. 2007, [Peer-reviewed], [Lead author]
English, Scientific journal, Matrix isolation infrared spectroscopy has been applied to study an ozone-water complex of atmospheric interest. The complex was identified in the spectral region of three normal modes of ozone and water. Ab initio calculation at MP4(SDQ), QCISD, and CCSD(T) levels indicates the existence of only one stable conformer, which accords with the present experimental result. This conformer belongs to the C-s symmetry group where two molecular planes of ozone and water are perpendicular to the C-s symmetry plane. The binding energy was calculated to be 1.89 kcal/mol at the CCSD(T)/6-311++G(3df,3pd)//CCSD(T)/6-311++G(d,p) level of theory. The formation constant and atmospheric abundance of the ozone-water complex are estimated using the thermodynamic and spectroscopic data obtained.

Jet spectroscopy of arylmethyl radicals in the visible region: Assignment of low-frequency vibrational modes in diphenylmethyl and chlorodiphenylmethyl radicals
Tsuge, M., Hamatani, S., Kawai, A., Tsuji, K., Shibuya, K.
Physical Chemistry Chemical Physics, 8, 2, 256, 263, ROYAL SOC CHEMISTRY, 2006, [Peer-reviewed], [Lead author]
English, Scientific journal, The D-1-D-0 transitions of diphenylmethyl (DPM) and chlorodiphenylmethyl (CDPM) radicals were studied by laser induced fluorescence (LIF) spectroscopy in a supersonic jet. Laser induced fluorescence excitation and dispersed fluorescence (DF) spectra were obtained for DPM and CDPM radicals produced by ArF excimer laser (193 nm) photolyses of their chlorides. With the aid of the density functional theory (DFT) calculation, vibronic bands are assigned by comparing the observed LIF excitation spectra of the jet-cooled radicals with the single vibronic level DF spectra. Low-frequency vibrations of 55 and 53 cm(-1) in the ground and excited states, respectively, are assigned to the symmetric phenyl torsional mode of the DPM radical. The geometries of DPM in the ground and excited states are discussed with regards to observed spectra and DFT calculations. Similarly for the CDPM radical, symmetric phenyl torsional and Ph-C-Ph bending modes are assigned and the halogen-substitution effect in equilibrium geometry is discussed.

量子力学と宇宙化学　　　　　　　　　　　　　　　
柘植雅士, 数理科学, 61, 12, 60, 67, Dec. 2023, [Invited], [Lead author]

Carbon atoms can diffuse and react on the surface of interstellar ice
Tsuge, M, Molpeceres, G, Nature Astronomy, 7, 1280, 1281, 14 Sep. 2023, [Invited]
Springer Science and Business Media LLC

近赤外フェムト秒レーザーイオン化によるMALDIプルーム組成の解明および「準熱平衡モデル」に基づく数値シミュレーション
城田起郎, 柘植雅士, 彦坂泰正, 副島浩一, 星名賢之助, 質量分析総合討論会講演要旨集, 65th, 198, 01 May 2017
Japanese

キシレンのフェムト秒レーザーイオン化質量スペクトル:二価イオンにおけるメチル基転位ダイナミクス
腰越洋, 新發田美紀, 城田起郎, 柘植雅士, 星名賢之助, 分子科学討論会講演プログラム&要旨(Web), 9th, ROMBUNNO.4P013 (WEB ONLY), 2015
Japanese

放電ジェット生成分子種のフェムト秒レーザーイオン化質量スペクトル
宮武智哉, 小林将文, 城田起郎, 柘植雅士, 星名賢之助, 分子科学討論会講演プログラム&要旨(Web), 7th, ROMBUNNO.2P018 (WEB ONLY), 2013
Japanese

水素結合体のフェムト秒レーザー多重イオン化
星名賢之助, 萩原博, 柘植雅士, 日本化学会講演予稿集, 92nd, 2, 235, 09 Mar. 2012
Japanese

カルボン酸二量体のフェムト秒レーザー多重イオン化
天田まい, 佐藤恵葉, 柘植雅士, 星名賢之助, 分子科学討論会講演プログラム&要旨(Web), 6th, ROMBUNNO.1A16 (WEB ONLY), 2012
Japanese

MALDI法におけるアミノ酸レーザー脱離および衝突プロトン化機構の解明
柘植雅士, 八子雄太, 綿貫那美, 星名賢之助, 原子衝突研究協会年会講演概要集, 36th, 86, 09 Aug. 2011
Japanese

ギ酸二量体の強レーザー場解離性イオン化
星名賢之助, 萩原博, 柘植雅士, 日本化学会講演予稿集, 91st, 2, 386, 11 Mar. 2011
Japanese

エタノールクラスターの強レーザー場誘起解離性イオン化
星名賢之助, 柘植雅士, 日本化学会講演予稿集, 90th, 2, 364, 12 Mar. 2010
Japanese

マトリックス支援レーザー脱離イオン化(MALDI)法における反応素過程の解明:アミノ酸・マトリックス分子間衝突によるプロトン移動反応
柘植雅士, 星名賢之助, 日本化学会講演予稿集, 90th, 2, 336, 12 Mar. 2010
Japanese

MALDI過程におけるプロトン移動反応の寄与:アミノ酸プロトン化効率の系統的測定による評価
柘植雅士, 星名賢之助, 日本薬学会年会要旨集, 130th, 4, 97, 05 Mar. 2010
Japanese

強レーザー場によるエタンからのH₃⁺生成と水素転位
川村春菜, 柘植雅士, 星名賢之助, 田宮実, 石黒政路, 分子科学討論会講演プログラム&要旨(Web), 4th, ROMBUNNO.2P001 (WEB ONLY), 2010
Japanese

フェムト秒レーザー励起によるエタノールクラスターからのH₃O⁺脱離反応
星名賢之助, 柘植雅士, 原子衝突研究協会年会講演概要集, 34th, 46, 20 Aug. 2009
Japanese

Dissociative Ionization of Aliphatic Amino Acids in Intense Laser Fields
柘植雅士, 相川祐貴, 伊藤佑介, 星名賢之助, 日本化学会講演予稿集, 89th, 1, 273, 13 Mar. 2009
Japanese

Mechanism of H3O+ detachment reaction from alcohols induced by intense laser fields
城田起郎, 真野匠智, 柘植雅士, 星名賢之助, 日本化学会講演予稿集, 89th, 1, 270, 13 Mar. 2009
Japanese

強レーザー場によるエタノールクラスターからのH₃O⁺生成反応
星名賢之助, 柘植雅士, 分子科学討論会講演プログラム&要旨(Web), 3rd, ROMBUNNO.4P022 (WEB ONLY), 2009
Japanese

MALDI法におけるプロトン化アミノ酸の生成効率とプロトン親和力の相関測定
柘植雅士, 利根川篤史, 三浦奨大, 星名賢之助, 分子科学討論会講演プログラム&要旨(Web), 3rd, ROMBUNNO.2P001 (WEB ONLY), 2009
Japanese

フェムト秒レーザー励起により生成したフランカチオンの準安定解離過程
柘植雅士, 城田起郎, 星名賢之助, 化学反応討論会講演要旨集, 24th, 108, 01 Jun. 2008
Japanese

フェムト秒レーザー励起による有機分子からのH₃O⁺放出
城田起郎, 柘植雅士, 星名賢之助, 化学反応討論会講演要旨集, 24th, 156, 01 Jun. 2008
Japanese

アミノ酸の強レーザー場誘起解離性イオン化過程
柘植雅士, 相川祐貴, 伊藤佑介, 星名賢之助, 分子科学討論会講演プログラム&要旨(Web), 2nd, ROMBUNNO.4P072 (WEB ONLY), 2008
Japanese

強レーザー場励起によるアルコール類からのH₃O⁺脱離過程
城田起郎, 真野匠智, 柘植雅士, 星名賢之助, 分子科学討論会講演プログラム&要旨(Web), 2nd, ROMBUNNO.4P059 (WEB ONLY), 2008
Japanese

フェムト秒レーザ励起によるフラン類の解離性イオン化
柘植雅士, 城田起郎, 星名賢之助, 分子科学討論会講演要旨集(CD-ROM), 1st, 2P135, 24 Aug. 2007
Japanese

Jet spectroscopy and excited state dynamics of diphenylmethyl radical and its derivatives.
M Tsuge, S Hamatani, A Kawai, K Tsuji, K Shibuya, ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY, 227, U300, U300, Mar. 2004
AMER CHEMICAL SOC, English, Summary international conference

Chiral Ice Crystals in Space
Akira Kouchi, Takashi Shimonishi, Tomoya Yamazaki, Masashi Tsuge, Naoki Nakatani, Kenji Furuya, Hiromasa Niinomi, Yasuhiro Oba, Tetsuya Hama, Hiroyasu Katsuno, Naoki Watanabe, Yuki Kimura
IntechOpen, 22 Aug. 2022, English, Scholarly book, [Joint work]

Molecular and Laser Spectroscopy Advances and Applications: Volume 2
Masashi Tsuge, Yuan-Pern Lee, Chapter 5 - Spectroscopy of molecules confined in solid para-hydrogen
Elsevier, Jul. 2020, English, Scholarly book, Solid para-hydrogen (p-H2) has emerged as a novel low-temperature matrix host with unique characteristics associated with a quantum solid. In this chapter, we introduce p-H2 matrix-isolation spectroscopy, presenting instrumentation and methods, the properties of solid p-H2, and varied spectral applications. For stable molecules, infrared spectra of methane at high resolution, propene, CH3OH and CH3F with internal rotation, molecular complexes with ortho-H2, and ultraviolet spectra of NO are discussed. The diminished cage effect allows the preparation of free radicals from photolysis in situ, either directly or via bimolecular reactions, such as Cl + unsaturated hydrocarbons to form radical products. Another novel method is the production of protonated and hydrogenated species on electron bombardment during deposition at 3.2 K. We have applied this method to small molecules (e.g., OCS), proton-bound dimers (e.g., N2-H+-N2) and polycyclic aromatic hydrocarbons that might be the carriers of unidentified infrared bands in astronomy. Hydrogen addition and abstraction reactions are also studied with photolytically produced H atoms from Cl + H2 (v = 1); several reactions with nitrogen-containing molecules (e.g., HONO and formamide) revealed reaction networks that are important for chemical evolution in space. Finally we present a future perspective on research using p-H2 matrix-isolation spectroscopy., 12213477, [Contributor]

Methane formation via the sequential hydrogenation of carbon atoms on icy grains: A remarkable effect of adsorption states
M. Tsuge, G. Molpeceres, Y. Aikawa, N. Watanabe
nga-2024, 15 Nov. 2024, English, Oral presentation
12 Nov. 2024 - 15 Nov. 2024, 42098847

低温氷表面での炭素原子の振る舞い：吸着状態・表面拡散・メタン生成
柘植雅士
原子衝突学会第49回年会, 08 Aug. 2024, Invited oral presentation
07 Aug. 2024 - 09 Aug. 2024, 42098847, [Invited]

The photodesorption efficiency of OH radical on ice from ultraviolet to visible range
Ni-En Sie, Masashi Tsuge, Yoichi Nakai, Naoki Watanabe
Chemistry and Physics at Low Temperatures 2024, 08 Jul. 2024, Oral presentation
06 Jul. 2024 - 11 Jul. 2024, 42098847

The behavior of carbon atoms on water ice at low temperatures
Masashi Tsuge
Chemistry and Physics at Low Temperatures 2024, 08 Jul. 2024, Invited oral presentation
06 Jul. 2024, 42098847, [Invited]

Experimental investigations on the fate of carbon atoms on interstellar icy grains
Masashi Tsuge, Naoki Watanabe
39th Symposium on Chemical Kinetics and Dynamics, 12 Jun. 2024, English, Oral presentation
12 Jun. 2024 - 14 Jun. 2024, 32183705

Detection of free radicals on the surface of ice and its application to surface diffusion studies
Masashi Tsuge
Roadmap for astrochemical diffusion studies, 10 Apr. 2024, Nominated symposium
09 Apr. 2024 - 11 Apr. 2024, 42098847, [Invited]

可視光による氷表面からの OH ラジカル光脱離
柘植雅士
次世代アストロ 第4回 領域全体集会, 08 Mar. 2024, Oral presentation
07 Mar. 2024 - 08 Mar. 2024, 42098847

Experimental Investigations on the Behavior of Carbon Atoms on Amorphous Solid Water
Masashi Tsuge, Germán Molpeceres, Yuri Aikawa, Naoki Watanabe
Laboratory Astrophysics Workshop (ICE 2024), 21 Feb. 2024, Oral presentation
20 Feb. 2024 - 23 Feb. 2024, 42098848

Wavelength-dependent photodesorption of OH radicals in a visible range
Ni-En Sie, Masashi Tsuge, Yoichi Nakai, W.M.C. Sameera, Naoki Watanabe
Laboratory Astrophysics Workshop (ICE 2024), 21 Feb. 2024, Oral presentation
20 Feb. 2024 - 23 Feb. 2024, 42098847

The photodesorption of OH radical triggered by visible light
N.-E. Sie, M. Tsuge, Y. Nakai, W.M.C. Sameera, N. Watanabe
International Conference on Key Intermediates in Atmospheric Chemistry and Astrochemistry, 23 Jan. 2024, Poster presentation
23 Jan. 2024 - 25 Jan. 2024, 42098847

Experimental investigations on the behavior of free radicals on the surface of icy grain analogues
Masashi Tsuge, Naoki Watanabe
International Conference on Key Intermediates in Atmospheric Chemistry and Astrochemistry, 23 Jan. 2024, Poster presentation
23 Jan. 2024 - 25 Jan. 2024, 32183705, [Invited]

Photodesorption of hydroxyl radicals from ice surface induced by visible photons
Ni-En Sie, Masashi Tsuge, Yoichi Nakai, W.M.C. Sameera, Naoki Watanabe
原子衝突学会第48回年会, 25 Nov. 2023, Poster presentation
25 Nov. 2023 - 26 Nov. 2023, 42098847

極低温H2O氷における負電荷伝導
柘植 雅士, 北島 謙生, 中井 陽一, Sameera W.M, 渡部 直樹
第17回分子科学討論会, 14 Sep. 2023, Oral presentation
12 Sep. 2023 - 15 Sep. 2023, 43492799

Visible Light Induced Photodesorption of Hydroxyl Radicals from Amorphous Solid Water
Masashi Tsuge, Ayane Miyazaki, Ni-En Sie, W.M.C. Sameera, Yoichi Nakai, Tetsuya Hama, Hiroshi Hidaka, Akira Kouchi, Naoki Watanabe
The 15th International Conference on the Physics and Chemistry of Ice, 06 Sep. 2023, Oral presentation
03 Sep. 2023 - 08 Sep. 2023, 42098847

Penetration of nonenergetic hydrogen atoms into amorphous solid water and their reactions with embedded molecules
Masashi Tsuge, Akira Kouchi, Naoki Watanabe
2023 Kavli-IAU Astrochemistry Symposium, 13 Jul. 2023, Poster presentation
10 Jul. 2023 - 14 Jul. 2023, 32183705

Nuclear spin conversion of H2 on surfaces of interstellar grain analogs: Amorphous solid water, amorphous silicate, and diamond-like carbon
Masashi Tsuge, Kenji Furuya, Akira Kouchi, Naoki Watanabe
2023 Kavli-IAU Astrochemistry Symposium, 13 Jul. 2023, Poster presentation
10 Jul. 2023 - 14 Jul. 2023, 32183705

Morphology of H2O, CO2 and CO ices on refractory grains based on experiments using transmission electron microscopy　　　　　　　　　　　　　　　
Y. Kimura, M. Tsuge, Y. Oba, T. Yamazaki, H. Hidaka, N. Watanabe, A. Kouchi
2023 Kavli-IAU Astrochemistry Symposium, 11 Jul. 2023, Poster presentation
10 Jul. 2023 - 14 Jul. 2023

Photodesorption of OH radicals adsorbed on ice surface in a visible region
SIE, Nien, TSUGE, Masashi, NAKAI, Yoichi, SAMEERA, W.M, WATANABE, Naoki
38th Symposium on Chemical Kinetics and Dynamics, 08 Jun. 2023, English, Poster presentation
07 Jun. 2023 - 09 Jun. 2023, 42098847

Energy dissipation upon the ortho-to-para conversion of H2 on low temperature interstellar grain surfaces: Amorphous silicate, diamond-like carbon, and amorphous solid water
TSUGE, Masashi, KOUCHI, Akira, WATANABE, Naoki
38th Symposium on Chemical Kinetics and Dynamics, 08 Jun. 2023, English, Poster presentation
07 Jun. 2023 - 09 Jun. 2023, 32183705

Determination of the activation energy for diffusion of OH radicals on water ice　　　　　　　　　　　　　　　
MIYAZAKI, Ayane, TSUGE, Masashi, HIDAKA, Hiroshi, NAKAI, Yoichi, WATANABE, Naoki
38th Symposium on Chemical Kinetics and Dynamics, 08 Jun. 2023, English, Oral presentation
07 Jun. 2023 - 09 Jun. 2023

Diffusive hydrogenation of molecules embedded in amorphous solid water
Masashi Tsuge, Akira Kouchi, Naoki Watanabe
Symposium on Next Generation Astrochemistry, 29 Nov. 2022, English, Poster presentation
29 Nov. 2022 - 02 Dec. 2022, 32183705

Production of isoquinolinium (iso-C9H7NH+) and isoquinolinyl radical (iso- C9H7NH, 1-iso-HC9H7N, and 3- to 8-iso-HC9H7N in solid para-hydrogen　　　　　　　　　　　　　　　
Prasad Ramesh Joshi, Masashi Tsuge, Chih-Yu Tseng, Yuan-Pern Lee
The 6th Asian Workshop on Molecular Spectroscopy, 04 Oct. 2022, Oral presentation
02 Oct. 2022 - 05 Oct. 2022

星間塵表面における水素分子のオルソ―パラ転換過程　　　　　　　　　　　　　　　
柘植雅士, 香内晃, 渡部直樹
第16回分子科学討論会, 21 Sep. 2022, Oral presentation
19 Sep. 2022 - 22 Sep. 2022

Ortho-to-para Nuclear Spin Conversion of H2 on Bare Interstellar Dust Analogs: Amorphous-silicate, Diamond-like Carbon, and Graphite　　　　　　　　　　　　　　　
Masashi Tsuge, Akira Kouchi, Naoki Watanabe
THE 22ND INTERNATIONAL VACUUM CONGRESS, 14 Sep. 2022, Oral presentation
11 Sep. 2022 - 16 Sep. 2022

模擬星間塵表面における水素分子の核スピン転換過程：表面フォノンによるエネル ギー散逸　　　　　　　　　　　　　　　
柘植雅士, 香内晃, 渡部直樹
原子衝突学会第 47 回年会, 08 Sep. 2022, Poster presentation
08 Sep. 2022 - 09 Sep. 2022

パラ水素マトリックス単離法によるイオン・ラジカルの赤外分光　　　　　　　　　　　　　　　
柘植雅士
冷却分子・精密分光シンポジウム, 26 Aug. 2022, Oral presentation
26 Aug. 2022 - 26 Aug. 2022

Experimental studies on the behavior of hydrogen on bare grain surfaces and within icy grains　　　　　　　　　　　　　　　
Masashi Tsuge
Chemistry and Physics at Low Temperatures, 04 Jul. 2022, Invited oral presentation
03 Jul. 2022 - 08 Jul. 2022, [Invited]

Energy dissipation process upon the nuclear-spin conversion of H2 on model interstellar grain surface　　　　　　　　　　　　　　　
Masashi Tsuge, Akira Kouchi, Naoki Watanabe
Energy Dissipation at Interfaces: From Catalysis to Astrochemistry, 16 May 2022, English, Poster presentation
16 May 2022 - 20 May 2022

Icy grains are not spherical nor ellipsoidal　　　　　　　　　　　　　　　
M. Tsuge, A. Kouchi, T. Hama, Y. Oba, S. Okuzumi, S.-i. Sirono, M. Momose, N. Nakatani, K. Furuya, T. Shimonishi, T. Yamazaki, H. Hidaka, Y. Kimura, K.-i. Murata, S. Tachibana, N. Watanabe
Workshop on Interstellar Matter 2021, 18 Nov. 2021, Invited oral presentation
17 Nov. 2021 - 19 Nov. 2021, [Invited]

A new electrochemical property of ice: negative charge transport triggered by reactions of surface OH radicals with electrons　　　　　　　　　　　　　　　
K. Kitajima, Y. Nakai, W. M. C. Sameera, M. Tsuge, A. Miyazaki, H. Hidaka, A. Kouchi, N. Watanabe
Workshop on Interstellar Matter 2021, 17 Nov. 2021, Poster presentation
17 Nov. 2021 - 19 Nov. 2021

Detection of photodesorption OH radicals from H2O ice surface by visible light　　　　　　　　　　　　　　　
Ayane Miyazaki, Naoki Watanabe, W. M. C. Sameera, Yoichi Nakai, Masashi Tsuge, Testuya Hama, Hiroshi Hidaka, Akira Kouchi
Workshop on Interstellar Matter 2021, 17 Nov. 2021, Poster presentation
17 Nov. 2021 - 19 Nov. 2021

Ortho-to-para nuclear spin conversion of H2 on interstellar bare grain analogues　　　　　　　　　　　　　　　
M. Tsuge, T. Namiyoshi, K. Furuya, A. Kouchi, N. Watanabe
Workshop on Interstellar Matter 2021, 17 Nov. 2021, Poster presentation
17 Nov. 2021 - 19 Nov. 2021

Diffusive hydrogenation of CO embedded in amorphous solid water at temperature up to 70 K　　　　　　　　　　　　　　　
M. Tsuge, H. Hidaka, A. Kouchi, N. Watanabe
Workshop on Interstellar Matter 2021, 17 Nov. 2021, Poster presentation
17 Nov. 2021 - 19 Nov. 2021

低温H2O氷表面でのOHラジカルの拡散　　　　　　　　　　　　　　　
宮﨑 彩音, 渡部 直樹, 柘植 雅士, Sameera W.m.c, 日高 宏, 香内 晃
第15回分子科学討論会, 20 Sep. 2021, Oral presentation
18 Sep. 2021 - 21 Sep. 2021

低温Ｈ2Ｏ氷表面からのOHラジカルの可視光脱離過程　　　　　　　　　　　　　　　
柘植 雅士, 宮﨑 彩音, Sameera W.m.c, 中井 陽一, 羽馬 哲也, 日高 宏, 香内 晃, 渡部 直樹
第15回分子科学討論会, 20 Sep. 2021, Oral presentation
18 Sep. 2021 - 21 Sep. 2021

Experimental studies on the behavior of hydrogen on bare grain surfaces　　　　　　　　　　　　　　　
Masashi Tsuge
Astrochemical Frontiers 2021, 05 Jul. 2021, English, Invited oral presentation
05 Jul. 2021 - 09 Jul. 2021, [Invited]

Infrared spectroscopy of protonated carbon monoxide dimer H+(CO)2　　　　　　　　　　　　　　　
Masashi Tsuge
Asian Workshop on Molecular Spectroscopy 2021, 09 Mar. 2021, English, Oral presentation
09 Mar. 2021 - 10 Mar. 2021

ELECTRONIC AND VIBRATIONAL STRUCTURE OF BUCKY BOWL　　　　　　　　　　　　　　　
Masaaki Baba, Ayumi Kanaoka, Masatoshi Misono, Hidehiro Sakurai, Masashi Tsuge, Pavithraa Sundararajan, Yuan-Pern Lee
International Symposium on Molecular Spectroscopy, 19 Jun. 2019, English
[International presentation]

H2 formation on a low-temperature diamondlike carbon surface　　　　　　　　　　　　　　　
Masashi Tsuge, Tetsuya Hama, Yuki Kimura, Akira Kouchi, Naoki Watanabe
35st Symposium on Chemical Kinetics and Dynamics, 05 Jun. 2019, English, Poster presentation
[International presentation]

Infrared spectra of protonated and hydrogenated corannulene(C20H10) and sumanene (C21H12) using matrix isolation in solidpara-Hydrogen - Implications to the UIR bands　　　　　　　　　　　　　　　
P. Sundararajan, M. Tsuge, M. Baba, H. Sakurai, Y.-P. Lee
IAU Symposium 350Laboratory Astrophysics:From Observationsto Interpretation, 14 Apr. 2019, English, Poster presentation
[International presentation]

Infrared spectra of protonated and hydrogenated corannulene (C20H10) and sumanene (C21H12) using matrix isolation in solid para-Hydrogen　　　　　　　　　　　　　　　
P. Sundararajan, M. Tsuge, Y.-P. Lee
256th ACS National meeting - New Experimental techniques for Astrochemistry, 19 Aug. 2018, English, Oral presentation
[International presentation]

Infrared spectrum of proton-bound nitrogen dimer N2-H+-N2 in solid para-H2　　　　　　　　　　　　　　　
M. Tsuge, H.-Y. Liao, J.-L. Kuo, Y.-P. Lee
The 2nd Asian Workshop on Molecular Spectroscopy, 09 Mar. 2018

Infrared spectra of protonated CO2, OCS, and CS2 in solid para-H2　　　　　　　　　　　　　　　
Masashi Tsuge, Prasanta Das, Yuan-Pern Lee
The 17th Symposium on Molecular Spectroscopy, 19 May 2017

Infrared spectra of protonated species isolated in para-hydrogen matrices　　　　　　　　　　　　　　　
Masashi Tsuge, Yuan-Pern Lee
Chemistry and Physics at Low Temperatures 2016, Jul. 2016
[Invited]

HXeI···HY Complexes (Y = Br and I) in Solid Xenon: Blue Shifts of the H–Xe Stretching Mode upon Complexation　　　　　　　　　　　　　　　
M. Tsuge, S. Berski, M. Räsänen, Z. Latajka, L. Khriachtchev
Chemistry and Physics at Low Temperatures 2013, Jul. 2013
[International presentation]

二酸化炭素錯体形成によるギ酸の高エネルギー配座異性体の安定化　　　　　　　　　　　　　　　
M. Tsuge, K. Marushkevich, M. Räsänen, L. Khriachtchev
分子科学討論会, Sep. 2012

カルボン酸二量体のフェムト秒レーザー多重イオン化　　　　　　　　　　　　　　　
天田まい, 佐藤恵葉, 柘植雅士, 星名賢之助
分子科学討論会, Sep. 2012

水素結合体のフェムト秒レーザー多重イオン化
HOSHINA KENNOSUKE, HAGIWARA HIROSHI, TSUGE MASASHI
日本化学会講演予稿集, 09 Mar. 2012, Japanese

MALDI法におけるアミノ酸レーザー脱離および衝突プロトン化機構の解明
TSUGE MASASHI, YAGO YUTA, WATANUKI NAMI, HOSHINA KENNOSUKE
原子衝突研究協会年会講演概要集, 09 Aug. 2011, Japanese

ギ酸二量体の強レーザー場解離性イオン化
HOSHINA KENNOSUKE, HAGIHARA HIROSHI, TSUGE MASASHI
日本化学会講演予稿集, 11 Mar. 2011, Japanese

マトリックス支援レーザー脱離イオン化(MALDI)法における反応素過程の解明:アミノ酸・マトリックス分子間衝突によるプロトン移動反応
TSUGE MASASHI, HOSHINA KENNOSUKE
日本化学会講演予稿集, 12 Mar. 2010, Japanese

エタノールクラスターの強レーザー場誘起解離性イオン化
HOSHINA KENNOSUKE, TSUGE MASASHI
日本化学会講演予稿集, 12 Mar. 2010, Japanese

新潟薬科大学における6年制薬学教育でのICT活用(1)~Webプラウザを用いた講義音声配信と自己学習システムを用いた学習支援~
YAMAGUCHI TOSHIO, ASADA SHIN'ICHI, IIMURA NAHOKO, KITAGAWA KOKI, SATO KOJI, SUGIHARA TAKUMICHI, TSUGE MASASHI, FUKUHARA MASAHIRO, HONZAWA SHINOBU, UNO KANAKO
日本薬学会年会要旨集, 05 Mar. 2010, Japanese

MALDI過程におけるプロトン移動反応の寄与:アミノ酸プロトン化効率の系統的測定による評価
TSUGE MASASHI, HOSHINA KENNOSUKE
日本薬学会年会要旨集, 05 Mar. 2010, Japanese

フェムト秒レーザー励起によるエタノールクラスターからのH₃O⁺脱離反応
HOSHINA KENNOSUKE, TSUGE MASASHI
原子衝突研究協会年会講演概要集, 20 Aug. 2009, Japanese

Mechanism of H3O+ detachment reaction from alcohols induced by intense laser fields
SHIROTA TATSURO, MANO NARUTOSHI, TSUGE MASASHI, HOSHINA KENNOSUKE
日本化学会講演予稿集, 13 Mar. 2009, Japanese

Dissociative Ionization of Aliphatic Amino Acids in Intense Laser Fields
TSUGE MASASHI, AIKAWA YUKI, ITO YUSUKE, HOSHINA KENNOSUKE
日本化学会講演予稿集, 13 Mar. 2009, Japanese

フェムト秒レーザー励起による有機分子からのH₃O⁺放出
SHIROTA TATSURO, TSUGE MASASHI, HOSHINA KENNOSUKE
化学反応討論会講演要旨集, 01 Jun. 2008, Japanese

フェムト秒レーザー励起により生成したフランカチオンの準安定解離過程
TSUGE MASASHI, SHIROTA TATSURO, HOSHINA KENNOSUKE
化学反応討論会講演要旨集, 01 Jun. 2008, Japanese

フェムト秒レーザ励起によるフラン類の解離性イオン化
TSUGE MASASHI, KIDA OKIRO, HOSHINA KENNOSUKE
分子科学討論会講演要旨集(CD-ROM), 24 Aug. 2007, Japanese

OHラジカル・水錯体のマトリックス単離赤外分光
YOSHINOBU TAKEAKI, TSUGE MASASHI, AKAI NOBUYUKI, TSUJI KAZUHIDE, KAWAI AKIO, SHIBUYA KAZUHIKO
化学反応討論会講演要旨集, 12 Jun. 2007, Japanese

水酸基ラジカル‐水錯体のマトリックス単離赤外分光―D置換体の帰属―
YOSHINOBU TAKEO, AKAI NOBUYUKI, TSUGE MASASHI, TSUJI KAZUHIDE, KAWAI AKIO, SHIBUYA KAZUHIKO
日本化学会講演予稿集, 12 Mar. 2007, Japanese

ジフェニルメチルラジカルのLIFスペクトル―パラ位フッ素置換効果―
KAWATANI YASUHIRO, TSUGE MASASHI, TSUJI KAZUHIDE, KAWAI AKIO, SHIBUYA KAZUHIKO
日本化学会講演予稿集, 12 Mar. 2007, Japanese

O₃‐H₂O錯体の赤外吸収スペクトルによる帰属とその特異的な光反応
TSUGE MASASHI, TSUJI KAZUHIDE, KAWAI AKIO, SHIBUYA KAZUHIKO
分子構造総合討論会講演要旨集(CD-ROM), 24 Aug. 2006, Japanese

ネオンマトリックス中で単離したO₃‐H₂O錯体の赤外吸収スペクトルと光反応
TSUGE MASASHI, TSUJI KAZUHIDE, KAWAI AKIO, SHIBUYA KAZUHIKO
化学反応討論会講演要旨集, 06 Jun. 2006, Japanese

ジフェニルメチルラジカルのジェット分光~低波数モードの解析~
TSUGE MASASHI, HAMATANI SATOSHI, KAWAI AKIO, TSUJI KAZUHIDE, SHIBUYA KAZUHIKO
分子構造総合討論会講演要旨集(CD-ROM), 01 Sep. 2005, Japanese

ジフェニルメチルラジカル誘導体のLIFスペクトル
KAWATANI YASUHIRO, TSUGE MASASHI, KAWAI AKIO, TSUJI KAZUHIDE, SHIBUYA KAZUHIKO
分子構造総合討論会講演要旨集(CD-ROM), 01 Sep. 2005, Japanese

ジフェニルメチルラジカル誘導体のLIF励起スペクトル~フッ素導入の効果~
KAWATANI YASUHIRO, TSUGE MASASHI, KAWAI AKIO, TSUJI KAZUHIDE, SHIBUYA KAZUHIKO
化学反応討論会講演要旨集, 01 Jun. 2005, Japanese

ジフェニルメチルラジカルの大振幅振動―分散蛍光スペクトルによる解析―
TSUGE MASASHI, HAMATANI SATOSHI, KAWAI AKIO, TSUJI KAZUHIDE, SHIBUYA KAZUHIKO
化学反応討論会講演要旨集, 22 Jun. 2004, Japanese

トリフェニルメチルラジカルのLIFスペクトル~低波数モードの解析~
TSUGE MASASHI, HAMATANI SATOSHI, KAWAI AKIO, TSUJI KAZUHIDE, SHIBUYA KAZUHIKO
分子構造総合討論会講演要旨集(CD-ROM), 20 Sep. 2003, Japanese

ジフェニルメチルラジカル誘導体のジェット分光
HAMATANI SATOSHI, TSUGE MASASHI, TSUJI KAZUHIDE, KAWAI AKIO, SHIBUYA KAZUHIKO
光化学討論会講演要旨集, 04 Sep. 2002, Japanese

ジフェニルメチルラジカル誘導体のLIFスペクトル
TSUGE MASASHI, HAMATANI SATOSHI, KAWAI AKIO, TSUJI KAZUHIDE, SHIBUYA KAZUHIKO
化学反応討論会講演要旨集, 18 Jun. 2002, Japanese

HXeY···H2O Complexes (Y = Cl, Br, and I) in Solid Xenon: Stabilization/Destabilization Effects　　　　　　　　　　　　　　　
M. Tsuge, S. Berski, M. Räsänen, Z. Latajka, L. Khriachtchev
Horizons in Hydrogen Bond Research
[International presentation]

2021 - Present
原子衝突学会　　　　　　　　　　　　　　　

Present
JAPAN SOCIETY FOR MOLECULAR SCIENCE　　　　　　　　　　　　　　　

Present
日本分光学会　　　　　　　　　　　　　　　

極低温氷表面実験から解き明かす分子雲での酸素・窒素原子の行方
科学研究費助成事業
01 Apr. 2024 - 31 Mar. 2027
柘植 雅士
日本学術振興会, 基盤研究(B), 北海道大学, 24K00686

ラジカルの拡散が活性化させる星間塵表面での分子進化：複雑有機分子生成の鍵
科学研究費助成事業 基盤研究(A)
01 Apr. 2022 - 31 Mar. 2027
渡部 直樹, 柘植 雅士, Sameera W.M.C.
日本学術振興会, 基盤研究(A), 北海道大学, 22H00159

氷の半導体的性質:n型半導体としての機能発現機構の定量的解明　　　　　　　　　　　　　　　
国内研究助成 特別テーマ 「水を究める」研究
Oct. 2024 - Sep. 2025
公益財団法人 クリタ水・環境科学振興財団, Principal investigator, 24K029

Next Generation Astrochemistry: Reconstruction of the Science Based on Fundamental Molecular Processes
Grant-in-Aid for Transformative Research Areas (A)
Apr. 2023 - Mar. 2025
Masashi Tsuge
日本学術振興会, 学術変革領域研究(A), 北海道大学, Principal investigator, 23H03982

氷における負電荷伝導機構の解明
国内研究助成
Oct. 2023 - Sep. 2024
公益財団法人 クリタ水・環境科学振興財団, 特別テーマ 「水を究める」研究, 北海道大学, Principal investigator, 23D005

氷星間塵内部における新たな反応過程：原子の侵入・拡散・反応
科研費 基盤B
Apr. 2021 - Mar. 2024
柘植雅士
日本学術振興会, 基盤B, 北海道大学, Principal investigator

Diffusion of hydrogen atoms in astronomical ice grains
Grants-in-Aid for Scientific Research
Apr. 2018 - Mar. 2021
Masashi Tsuge
In the chemical evolution processes occurring within low temperature molecular clouds, it has been demonstrated that chemical reactions on icy grain surface play significant roles. However, chemical processes within ice mantle, which do not require photons and cosmic rays, have not been investigated. In this work, we aimed at revealing whether hydrogen atoms can penetrate into ice mantles or not.
We found that hydrogen atoms penetrate into amorphous solid water and react with embedded atoms or molecules. The most important finding of this work is that hydrogen reactions occur above 20 K, where efficiency of surface hydrogen reactions is extremely low.
JSPS, Grant-in-Aid for Scientific Research (C), Hokkaido University, Principal investigator, Competitive research funding, 18K03717

Investigation of dressed-state formation mechanism by spectroscopic measurements
Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
Apr. 2008 - Mar. 2011
HOSHINA Kennosuke, TSUGE Masashi
Fragmentation paths through fast hydrogen migration within ionized organic molecules by an intense femtosecond laser field were investigated based on measured ion yields and results of the quantum chemical calculation. The H_3O^+ ejection paths via C_2H_4OH^+ for ethers and alcohols, and via C_2H_5OH_2^+ for ethanol dimer, and their time scales were clarified. In the experiment using deuterium-labeled ethane, CH_3CD_3, it was demonstrated from H/D mixing ratios in the H_2^+,H_3^+,H_2 fragments that a reaction path through a CH_2CH_2^<2+>…H_2 complex produces H_2 and H_3^+ fragments.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), Nigata University of Phermacy and Applied Life Sciences, Coinvestigator, 20550023

The surprising organic chemistry in interstellar space　　　　　　　　　　　　　　　
18 Mar. 2024
Other than myself
Royal Society of Chemistry
Chemistry World
[Pr]

Carbon Atoms Diffuse on Interstellar Ice Grains To Form Complex Organic Compounds
18 Sep. 2023
SciTechDaily, [Internet]

Carbon atoms coming together in space
14 Sep. 2023
ScienceDaily, [Internet]

Researchers investigate how carbon atoms might diffuse on interstellar ice grains
14 Sep. 2023
Phys.org, [Internet]

International committee member of Asian Workshop on Molecular Spectroscopy　　　　　　　　　　　　　　　
Mar. 2024 - Present
Planning etc
Academic society etc

Chemistry and Physics at Low Temperatures 2024　　　　　　　　　　　　　　　
06 Jul. 2024 - 11 Jul. 2024
Planning etc
Academic society etc

The 7th Asian Workshop on Molecular Spectroscopy (Chair)
05 Nov. 2023 - 08 Nov. 2023
Planning etc
Masashi Tsuge
32183705

The 6th Asian Workshop on Molecular Spectroscopy　　　　　　　　　　　　　　　
02 Nov. 2022 - 05 Nov. 2022
Planning etc
Competition etc